Many years ago, I had used the wrong image data to flash my BIOS chip. This resulted in a failed BIOS upgrade & a corrupt BIOS. After that unsuccessful procedure, I was no longer able boot my HP Pavilion. After searching on the Internet using the iMac, (That's the point I keep multiple computers at home: I can always have back up when someting goes wrong.) I finally find a solution: hot-swapping the BIOS chip.
The principle: the BIOS is used only for the booting of the PC & exists outside of the scope of the Operating System. After booted into the Windows OS, you no longer need it to keep the machine running. So you can find a normal PC, which has the same flash mechanism with your PC. For most modern Pentium II and III motherboards, the flash mechanism is the same. Boot it to the DOS prompt, remove the BIOS chip while the computer is still running. replace the bad BIOS to the slot, run the flash utility to write the correct BIOS code into the bad BIOS chip. Then, shut off the normal machine, pull out the recovered BIOS chip, return the original BIOS to the normal machine. That's all. You should be able to use the recovered BIOS to boot you machine.
To note, the hot-swapping method can used to recover the BIOS chips damaged by the infamous CIH virus.