That is correct, it’s been quite awhile now since UEFI became standard but almost everyone still calls it the BIOS. Although I’ve noticed the word firmware is starting to be used more as well.

Looks awesome. How much space is between the batteries? Could you push air through the gaps to cool them?

I’m curious about the failures. Have you been repeatedly poisoning yourself trying to figure this out?

I was looking into Fairphone and got sketched out, they do not really seem particularly trustworthy or competent.

For example: https://discuss.grapheneos.org/d/24134-devices-lacking-standard-privacysecurity-patches-and-protections-arent-private

Not an expert but I would look into replacing the control board itself rather than trying to fix it. If you can reset it, I would guess it uses a jumper like on an oldschool motherboard.