[kijin]

I once managed to brick a PC motherboard that advertised "dual BIOS". It didn't fallback to the previous version after a botched BIOS update.

It's totally possible that the update corrupted the other bootslot as well. If those blocks aren't off-limits to the updater program, it's just an off-by-one error waiting to happen. Slot 0 or slot 1?

Another possibility is that the updated version booted up just enough not to trigger the automatic fallback, and then got stuck in a loop.

[Telaneo]

It's not even that long ago that dual-BIOS boards had a physical switch to toggle between them. Guess that got cost-cut out of existence.