While I'm not completely sure I understand your problem, since your motherboard will POST, you might try doing a hotswap BIOS flash. Get it ready to flash, then swap in your original BIOS chip and reflash it to the correct BIOS for your motherboard. Here is a good guide for a hotswap BIOS flash:
http://www.short-media.com/forum/showthread.php?t=25538
Good luck!