[pgeorgi]

All chromebooks allow to completely overwrite the firmware.

It requires opening the machine though (and then turning a screw), both as a crude security measure (it's not a drive-by attack if it takes 10 minutes of physical access) and a stability guarantee (without the modification, the system basically can't be stuck, no matter how broken an update might be).

Disclosure: I work on Chrome OS firmware.

[rrego]

I suppose I've been reading third party documentation.

https://wiki.archlinux.org/index.php/Chrome_OS_devices/Chrom...

Along with the link above indicates otherwise. Are these websites both wrong?

I did completely overwrite the firmware for my Acer c720 (by removing that write protect screw) but I assumed that was an exception.

[pgeorgi]

The write protect screw (or a similar mechanism) exists and works the same way on every Chromebook.