For mine I was able to go back BIOS by BIOS (had to go one by one, could not go back more than that in one flash) quite a ways but did reach a point that it would not let me go back any farther. I believe I was at bios 0903? Anyways, I wanted to try the mod bios 0030 for unlocking and had trouble getting back. I ended up doing some google searching and found a version of AFIDOS that let me flash back to whatever I wanted, but it was not the version downloaded from Asus. When I get back home I will see if I still have it and can put it online to download or email it if you can't find it.