|Your best chance is to see if the computer manufacturer supplies some way of reversing the BIOS flash.|
I take it you had good reason to do this because it should only be done (with utmost care) to cure a listed specific issue or when fitting a different CPU. BIOS updates are not like other updates and always carry the risk of bricking the motherboard.
You can look through this lot I guess, but I didn't find anything too promising that appeared to produce a fix:
I also found this very general Lenovo discussion about restoring a Phoenix BIOS flash:
You would obviously have to get the download onto a flash drive using another computer.
Always pop back and let us know the outcome - thanks
message edited by Derek