[Matt Devo]

A lot of chromebox guides explain that in order to update the chromebox firmware you have to remove the FW write-protect screw. I assume this will only disable the flash chip write protection pin so the chip can be written to. My question is do I have to put the screw back after flashing new firmware? Any reason not to?

yes you must remove the WP screw to flash the firmware, no you don't want to put it back in, as it will just complicate things if you want to go back to stock later

Dear Mr. Matt Devo! I've seen that I can update my chromebox with a coreboot/SeaBIOS payload, but there is also progress on a Tianocore UEFI image (Source: https://mrchromebox.tech ). Can you perhaps explain what the advantages are for each image and suggest which one to go for?

The Legacy BIOS payload (SeaBIOS) is just that -- Legacy. Originally the firmware offered here used SeaBIOS, but once we had the UEFI firmware running as well/better, I switched to that. The legacy firmware is no longer updated and the UEFI firmware contains many fixes/tweaks not in the legacy firmware.

I've seen the stock coreboot firmware has enabled the verified boot for the ChromeOS. Can I achieve something similar by updating the firmware with either SeaBIOS or Tianocore coreboot image?

no, verified boot requires the use of the ChromeOS payload (depthcharge) and would require significant work to have it boot another OS, so I don't use it.

If I want to compile the coreboot image myself, is this the correct address for the source code? What's the difference between this repository and the coreboot mainline git repository (review.coreboot.org)?

that's the correct address for coreboot, but you also need the payload to go with it (SeaBIOS or Tianocore) but my repos for those are also located on my github. Building your own firmware isn't easy/straightforward but if you're going to do so, then using my scripts/repos is the way to go. In terms of differences between my repos and the main/upstream ones, I have a large amount of tweaks/fixes etc on top of the upstream repos which are necessary to build or provide enhanced functionality. When looking at the commit history for my repos, my commits are always on top so it's easy to see what I've added

All you need to do is follow the guide here, but install Mint instead of LibreELEC. Then post install, you'll likely need to "fix" the bootloader as described on the FAQ on my website. Otherwise, everything will work perfectly