Removing Chrome OS
Introduction
A long time ago, the school were I work got rid of lots of Acer C731 Chromebooks. The device no longer received new versions of Chrome OS so lots of vendors stopped supporting it. I think that is a bit of a waste because even though some were heavily used it, many still had life in them.
A quick tanget, it is sad that newer devices do not make alternate OSes easy. Read up on MrChromebox.tech to learn more about firmware and booting.
Anyway, before we got to where we are today, I grabbed an Acer C731 and put Linux on it. The usual process I do when I get a device that is abandoned. The tl;dr is Chrome OS Flex was cool, but audio is busted (on purpose?) and only Bunsen Labs performed well.
Table of Contents
Steps
Reload Chrome OS: Better said, do the recovery process. Even though folks say don't do it for phones, you are better off doing it here. Especially if you are using a device that was deprovisioned from any type of enterprise Google domain. Follow Google's "Download a new copy of the OS" instructions.
Onboard Process: In short, log into the Chromebook after recovery. If the device was once part of an enterprise Google domain, you will have to to reset the domain settings. Especially if they disabled Developer Mode.
Enable Developer Mode: Google has this page, but there are different options. Sometimes depending on the device. For the Acer C731:
Power-off the device.
Hold ESC + REFRESH, power on the device. Let go when you see the "Missing or Damaged" screen.
Press CTRL + D.
Press ENTER to confirm. NOTE: Doing so will erase everything on the Chromebook!
Wait until after Chrome OS resets itself (about 10 - 15 minutes).
After another reboot, booting will pause on a "page" saying "Press SPACE to re-enable". DO NOT do this as it will get you out of Developer Mode.
Wait 20 seconds and you will get to the setup or onboarding screen again. But in a developer enabled version of Chrome OS. You DO NOT need to go through this if you just want to install Linux or CloudReady.
Get a command prompt: Now press CTRL + ALT + FWD (basically where F2 is located) to get a Linux prompt (yes Chrome OS is Linux!).
Log in with "chronos": No password needed.
Load Firmware: Go to MrChomeboox.tech's page on Firmware script to install the script. I suggest you read the whole website. Again, really know what you are doing.
Update the RW_LEGACY firmware: And reboot; I like to test things in stages. Meaning this is less intrusive and if it doesn't work, something else is up.
Check Firmware: After the reboot, wait the 20 seconds, press CTRL + ALT + FWD, login as chronos and run "sudo firmware-util.sh" to see differences.
Power-off the device.
Write Protect Screw: If you device has one, open the device up and remove the "Write Protect" screw. Ignore references to Windows 10. ;-)
Firmware Again: Go through the process to get to running the firmware script again.
No Going Back: Be certain you want to NOT boot (an outdated) Chrome OS!!!
New Boot Firmware: If you said yes above, in the script's CLI, install "UEFI (Full ROM) Firmware". I suggest backing up the firmware; don't use Chrome OS recovery USB. After all the install/backup prompts, you will get back to the main menu.
Linux USB & then reboot: Plug in a USB with an EFI supporting Linux distro you want to install and then choose reboot.
Sign it worked: You should get a rabbit logo during boot, which is the new EFI firmware.
Install Linux: Read below for various distro comments.
Firmware, last time: After booting & installing Linux, go back to MrChomeboox.tech's page on Firmware script to install the script under Linux. You might never need it now, but why not just in case? :-)
So what happened after all that? I first installed Lubuntu 22.04; the "30 second review" is that it was a mixed bag. The positive side of the spectrum is that local apps run quite well. Even heavy ones like Libre Office and Clementine, at the same time. The other end is that web browsers are known RAM hogs. Even after some optimization (swappiness, noatime), Chrome brought the C731 to its knees. Firefox faired better, though leaving YouTube Music running and checking email, the machine locked up in 10 minutes or so.
I already mentioned Chrome OS Flex. It performs well, but the sound doesn't work. Greedy, er, silly Google!
The only Linux distro that I liked the performance was Bunsen Labs. Don't expect much. But I could have YouTube Music playing, check Gmail, and then start browsing.