When I received a broken Chromebook to play with, I had assumed it was long out of support and my thoughts went to how I might install some operating system other than ChromeOS on it. Then I found that it actually still had some supported lifespan left so I decided to keep it as a Chromebook for occasional use. That supported life ended in September 2021, now it very bluntly tells me to buy a newer model: there will be no more Chrome OS after 92.

Time again to revisit the “install other OS” issue, starting with the very popular reference Mr. Chromebox. Where I learned newer (~2015 and later) Chromebooks are very difficult to get working with other operating systems. I guess this 2014 vintage Chromebook is accidentally close to optimal for this project. Following instructions, I determined this machine has the codename identifier “Swanky” and I have the option to replace default firmware with an implementation of UEFI, in theory allowing me to install any operating system that runs on this x86-64 chip and can boot off UEFI. But first, I had to figure out how to deactivate a physical write protect switch on this machine.

The line “Fw WP: Enabled” is what I need to change to proceed. Documentation on Mr. Chromebox site said I should look for a screw that grounds a special trace on the circuit board. Severing that connection would disable write protect. I found this guide on iFixit, but it is for a slightly different model of Toshiba Chromebook with different hardware. That is a CB35-C3300 and I have a CB35-B3340. The most visible difference is that CPU has active cooling with a heat pipe and fan, but the machine in front of me is passively cooled.

So I will need to find the switch on my own. Starting with looking up my old notes on how to open up this machine and get back to the point where I could see the metal shield protecting the mainboard.

With the bottom cover removed, I have a candidate front and center.

This screw has a two-part pad that could be grounding a trace, though there is an unpopulated provision for a component connected to that pad. This may or may not be the one. I’ll keep looking for other candidates under the metal shield.

A second candidate was visible once the metal shield was removed. And this one has a little resistor soldered to half of the pad.

I decided to try this one first.

I took a thin sheet of plastic (some random product packaging) and cut out a piece that would sit between the split pad and the metal shield with screw.

That was the correct choice, as firmware write-protection is now disabled. I suspect candidate #1 could be used for chassis intrusion protection (a.k.a. “has the lid been removed”) but at this point I have neither the knowledge or the motivation to investigate. I have what I want, the ability to install UEFI (Full ROM) Firmware.

What happens now? I contemplated the following options:

1. Install Gallium OS. This is a Linux distribution based on Ubuntu and optimized for running on a Chromebook.
2. I could go straight to the source and install Ubuntu directly. Supposedly system responsiveness and battery life won’t be as good, and I might have more hardware issues to deal with, but I’ll be on the latest LTS.
3. Or I can stay with the world of Chrome and install a Chromium OS distribution like Neverware CloudReady.

Looking at Gallium, I see it purports to add hardware driver support missing from mainline Ubuntu and stripping things down to better suit a Chromebook’s (usually limited) hardware. There were some complaints that some of Ubuntu’s user-friendliness was trimmed along with the fat, but the bigger concern is that Gallium OS is based on Ubuntu 18 LTS and has yet to update to Ubuntu 20 LTS. This is very concerning as Ubuntu 22 LTS is expected to arrive soon. [UPDATE: Ubuntu 22 LTS “Jammy Jellyfish” has been officially released.] Has the Gallium project been abandoned? I decided to skip Gallium for now, maybe later I’ll decide it’s worth a try.

I already had an installation USB drive for Ubuntu 20.04 LTS, so I tried installing that. After about fifteen minutes of playing around I found a major annoyance: keyboard support. A Chromebook has a different keyboard layout than standard PC laptops. The Chromebook keys across the top of the keyboard mostly worked fine as function keys, but there are only ten keys between “Escape” and “Power” so I didn’t have F11 or F12. There is no “Fn” key for me to activate their non-F-key functions, such as adjusting screen brightness from the keyboard. Perhaps in time I could learn to navigate Ubuntu with a Chromebook keyboard, but I’ve already learned that I have muscle memory around these keys that I didn’t know I had until this moment. It was also missing support for this machine’s audio device, though that could be worked around with an external USB audio device like my Logitech H390 headset. (*) It is also possible to fix the audio issue within Ubuntu, work that Gallium OS supposedly has already done, but instead of putting in the work to figure it out I decided on the third option.

It’s nice to have access to the entire Ubuntu ecosystem and not restricted to the sandbox of a Chrome OS device, but I already have Ubuntu laptops for that. This machine was built to be a small light Chromebook and maybe it’s best to keep it in that world. I created an installation USB drive for Neverware CloudReady and returned this machine to the world of Chrome OS. Unlike Ubuntu, the keyboard works in the Chrome OS way. But like Ubuntu, there’s no sound. Darn. Oh well, I usually use my H390 headset when I wanted sound anyway, so that is no great hardship. And more importantly, it puts me back on the train of Chromium OS updates. Now it has Chromium OS 96, and there should be more to come. Not bad for a Chromebook that spent several years dumped in a cabinet because of a broken screen.

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When I got my hands on this Toshiba Chromebook 2 (CB35-B3340) its primary screen was cracked and unreadable. I was happy when I discovered I could use it as a Chromebox by an external HDMI monitor, but I quickly found the limitation of that approach when I tried to switch the device into developer mode: those screens were only visible on the screen I couldn’t read.

Google has published instructions for putting a Chromebook into developer mode, but they weren’t specific enough for use with an unreadable screen. It doesn’t say how many menus are involved, and it doesn’t say how much time to expect between events. Probably because these details vary from device to device and not suitable for a general document.

I looked around online for information from other sources and didn’t find enough to help me navigate the procedure. Most irritating are the sites that say things like: “And from this point just follow the on screen prompts” when the whole point was I couldn’t read those prompts at the time.

Now that I’ve installed a replacement screen, I can see what happens and more importantly, I can now document the information I wished I was able to find several weeks ago. The most surprising part to me was that it took roughly seven minutes to transition into developer mode, but less than a minute to transition out of it. Since all user data are erased in both of these transitions, I’m curious why the times are so different.

In any case, I’ve captured the process on video (embedded below) and here is the timeline for putting a Toshiba Chromebook 2 into developer mode even if the screen is not readable. Times are in (minutes:seconds)

• Preparation: power down the device.
• (0:00) While holding down [ESC] + [REFRESH], press [POWER].
• (0:15) Press [CONTROL] + [D] to enter developer mode
• (0:25) Press [ENTER] to confirm
• (0:36) Press [CONTROL] + [D] to confirm
• (6:52) Two beeps warning user the Chromebook is in developer mode.
• (7:25) Chrome OS booted up into developer mode and ready to be mirrored to external monitor.

Following power-ups while in developer mode:

• (0:00) [POWER] button as normal (no other keys needed)
• (0:10) Press [CONTROL] + [D] to bypass 30-second developer mode warning screen, also skipping the two beeps.
• (0:20) Chrome OS booted up into developer mode and ready to be mirrored to external monitor.

Exiting Developer Mode:

• Preparation: power down the device.
• (0:00) [POWER] button as normal
• (0:08) Press [SPACE] to re-enable OS verification.
• (0:15) Press [ENTER] to confirm
• (0:48) Chrome OS booted up into normal mode and ready to be mirrored to external monitor.

Ever since I started looking at this Toshiba Chromebook 2 (CB35-B3340) I had been focused on how I can break out of constraints imposed by Chrome OS. Although I had occasionally acknowledged the benefits of a system architecture focused on the most popular subset of all computing activities, I still wanted to know how to get out of it.

Now that my research got far enough to learn of a plausible path to removing all constraints and turning this Chromebook into a normal Ubuntu laptop, I’m satisfied with my available options and put all that aside for the moment. I took the machine out of Chrome OS Developer Mode so I could experience using a Chromebook for its original intended purpose and seeing how well it fills its designated niche.

Reviewing all the security protections of Chrome OS during the course of my adventure made me more willing to trust one. If I didn’t have my own computer on hand and needed to use someone else’s, I’m far more likely to log into a Chromebook than an arbitrary PC. Chrome OS receives frequent updates to keep it secure, raising the value of continued support. Since my original session to fast forward through four years of updates, I’ve received several more just in the few weeks I’ve been playing with this machine.

On the hardware side, this lightweight task-focused machine has lived up to the expectation that it would be more pleasant to use than a bulky jack of all trades convertible tablet of similar vintage. Its secondhand replacement screen‘s visual blemishes have not been bothersome, and the keyboard and trackpad had been responsive to user input. Its processing hardware is adequate, but not great. During light duty browsing the estimated battery life stretches past eight hours. But if a site is loaded down with ads and tracking scripts, responsiveness goes down and battery life estimate quickly nosedives under 4 hours.

The biggest disappointment in processing power comes from the display department. This machine was the upgraded model with a higher resolution 1920×1080 panel instead of the standard 1366×768. The higher resolution made for more pleasantly readable text, but constantly updating those pixels was too much for the machine to handle. It couldn’t sustain web video playback at 1080p. Short clips of a few seconds are fine, but settling down to watch something longer would be frustrated with stutters unless the video resolution was lowered to 720p.

And finally, there’s the fact that when the network connection goes down, a Chromebook becomes largely useless. This is unfortunately more common than I would like at the moment as I’m having trouble with my new router. In theory Google offers ways for web sites to remain useful on a Chromebook in the absence of connectivity (like Progressive Web Apps) but adoption of such techniques has not yet spread to the sites I frequent. So when the router crashes and reboots itself, the Chromebook becomes just a picture frame for showing the “No internet” error screen. This is not a surprise since network connectivity is a fundamental pillar of Chrome OS, but it is still annoying.

All things considered, a Chromebook is a nice lightweight web appliance that makes sense for the right scenarios. Its focused scope and multilayered security provisions mean I would heartily recommend one for the technically disinclined. If they learn enough technology to find Chrome OS limiting, there’s always Mr. Chromebox. If I should buy one for my own use, I would want a high resolution panel, and now I also know to get a more powerful processor to go with it.

If I couldn’t solve the challenges getting ROS up and running with Ubuntu 18 under Crouton in Chrome OS, there is yet another option: erase Chrome OS completely and install Ubuntu in its place. I understand this would remove the developer mode warning and menu, and the software startup can go straight into ROS via an Ubuntu service just like any other Ubuntu machine.

The internet authority for this class of modification is Mr. Chromebox. I don’t know who this person is, but all my web searches on this topic inevitably points back to some resource on https://mrchromebox.tech. Starting with the list of alternate operating system options for a Chromebook. Ubuntu is not the only option, but for the purposes of a robot brain, I’m most interested in the option of a full UEFI ROM replacement allowing me to install Ubuntu like any other UEFI computer.

In order to install Mr. Chromebox’s ROM replacement, the hardware must on the list of supported devices. Fortunately the Toshiba Chromebook 2 (CB35-B3340) is represented on the list under its Google platform name “Swanky” so it should be eligible for the firmware utility script that makes the magic happen.

Before running the script, though, there are some hardware modifications to be made. Firmware replacement can undercut security promises of a Chromebook, even more than developer mode, so there are protections that require deliberate actions by a technically capable user before the firmware can be replaced. For “Swanky” Chromebooks, this hardware write-protect switch is in the form of a screw inside the case that makes an electrical connection across two contacts on the circuit board. Before the firmware can be replaced, that screw must be removed and the two pads insulated so there is no longer electrical contact.

Having a hardware component to the protection makes it very difficult for a Chromebook to be compromised by software bugs. Yet the screw + PCB design is a deliberate provision allowing modification with just simple hand tools. Such provisions to bypass hardware security is not found in many other security-minded consumer hardware, for example gaming consoles. I appreciate Google’s effort to protect the user, yet still offer the user an option to bypass such protection if they choose.

For the moment I am not planning to take this option, but it is there if I need it. In the near future I took this opportunity to get some first hand experience living with a Chromebook with its originally intended (non developer) use.

Having replaced a cracked and illegible screen with a lightly blemished but perfectly usable module, I can finally switch this Toshiba Chromebook 2 (CB35-B3340) into developer mode. It’s not a complicated procedure, but the critical menus are displayed only on the main display and not an external monitor. With the earlier illegible screen, there was no way to tell when I needed to push the right keys. I might have been able to do it blind if I had a timeline reference… which is a potential project for another day.

Today’s project was to get Crouton up and running on this Chromebook. Following instructions for the most mainstream path, I went through a bunch of procedures where I only had a vague idea of what was happening. Generally speaking it’s not a great idea to blindly run scripts downloaded from the internet, but Crouton is fairly well known and I had no personal data on this Chromebook, something enforced by Chrome OS.

Until I put this Chromebook into developer mode myself I hadn’t known that user data is erased whenever a Chrome OS device transitions into or out of developer mode. This meant whatever data is saved on a Chrome OS device can’t be snooped upon in developer mode. Also, any tools or utilities that might have been installed to view system internals in developer mode are erased and no longer usable once the machine is in normal mode. This policy increased my confidence in privacy and security of Chrome OS. I’m sure it’s not perfect as all software have bugs, but it told me they had put thought into the problem.

What it meant for me today was that everything I had put on that Chromebook was wiped before I could start playing with Crouton. Whose default instructions quickly got me up and running on Ubuntu 16 (Xenial) with the xfce desktop. Running two full user-mode GUI on top of a single kernel noticeably stresses this basic machine, with user response becoming a little sluggish. Other than that, it felt much like any other Ubuntu installation except it’s all running simultaneously with full Chrome OS on the exact same machine.

Raw performance concerns aside, it seemed to work well. And the wonder of chroot meant it’s pretty easy to erase and restart with a different configuration. Which is what I’ll tackle next, because ROS Melodic is intended for Ubuntu 18 (Bionic).

Once I discovered the support window for a Toshiba Chromebook 2 (CB35-B3340) extended longer than I had originally anticipated, I was more willing to spend money to bring it back to working condition. While I was shopping for a replacement screen earlier I saw several offers for new units and a few scattered offers for secondhand units. I presume these were salvaged from retired machines and resold, which is fine by me as it came at a significant discount. $47 with taxes and shipping (*), as compared to $75 (before taxes & shipping) for a new unit.

That ~40% discount also came with a caveat: I clicked “Buy” on a unit that was rated “Grade B: Fully functional but with visible blemishes.” It was a bit of a gamble, but my primary requirement is only to see enough to enter developer mode, so I decided I would tolerate visual blemishes to save a few extra dollars. There was also a bit of a gamble in shipping. from my disassembly efforts I knew this panel is very thin and fragile. This time around, I did not mind the extensive packaging of Amazon orders.

I saw no physical blemishes on the panel during installation. Once installed, I was happy to see Chrome OS boot up and run. I had to work hard to see the visual blemishes that earned this panel its Grade B rating. I had to set the screen to full black, and artificially increase contrast in a photo editor, before we can see the magenta smudges: Two light horizontal smudges, and two dots one of which look a bit smeared.

I’m not familiar with failure mode of LCD display modules so I have no idea what’s going on here. Perhaps these were manufacturing defects? In any case, these flaws are only visible if I strain to look for them and there is no physical damage to the screen so I’m satisfied with my purchase.

The visual blemishes are not at all bothersome in normal usage. This level of performance was more than good enough to be used as a normal Chromebook if I wanted to use it as such. But the reason I got the screen was to access Chrome OS recovery menu to enter developer mode, so I will try that first.

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(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.