A friend of mine recently built a system based around this motherboard, he upgraded the bios to v3003 and his system is now completely unstable, whea errors, nvme corruption etc


He wants to downgrade the bios but there is no flashback on this board, he has tried previous bioes using ezflash but nothing works, just get a message that it's not a proper bios etc.
flash drive is fat32, mbr, bios is correctly named.

Any idea how he can downgrade on this board as the latest bios has made his system unusable.