Make sure the BIOS ROM file is named correctly on a freshly fat 32 formatted low density stick like under 8MB and its plugged into the correct USB port. Dont even need a CPU. Ive done it with a GPU installed. When when you are all set just turn the power on.
How did your BIOS crap the bed? Did it corrupt during a flash and power loss? If the ROM chip is toast all the flashing in the world wont do a thing.