memory is vague since its ages since I did anything but check the manual for using the backup bios?
dual bios on gigabyte boards, rescued a bad bios update for me a few years back
there might be a key to hold down while you switch on
I did manage to get through a non booting bios once by creating a floppy that auto-run a bios load to the previous version (in autoexec.bat), so it didnt require a display, and that fixed another motherboard.
havent had bios problems in such a long time now though.
good luck