P35 DS3R BIOS rolled back too far, won't boot

I've been having issues with my P35 DS3R (Rev 2.1) lately and one of the threads I found in this forum said to try rolling back to the F4 BIOS. However, having found this information at 3am and possibly not thinking straight, it didn't occur to me that this was only a fix for the Rev 1.0 board.

Long story short, I booted up with a BIOS that my Rev 2.1 board doesn't recognize or something and now my computer won't start. Power comes on for a few seconds and it shuts down. Then it tries again in a few moments but perpetually fails until I flip the power switch in the back.

I have no problem wiping the entire computer clean as it's already been formatted 3 times this week in an attempt to fix the original problem. I've already tried to clear the CMOS and remove the MoBo battery. Neither has resulted in being able to boot the computer.

I feel rather nubish, and I've learned my lesson about fixing computers late at night. Any suggestions on how to get the computer to boot, even if wiping things clear is needed, is very much appreciated.