Where you store BIOS,which to be flashed?
Try to load Optimized defaults,reboot and try to flash.
Any additional USB device (except mouse,keyboard and USB FAT32 stick)...which can disrupt BIOS flashing?
As I said,no problem here at all.
Edit:
Once BIOS is flashed,will do 2 times On/Off and third time boot.
Will be helpfull to post your full spec.