here is how you boot back into the backup BIOS:

Method 1

    Switch off your computer
    Hold the power button until your computer starts and shuts down again
    Press the power button again, your backup BIOS should kick in now and should re-flash the backup BIOS if there's anything wrong with the new one.

Method 2

    Switch off your computer
    Hold the power AND the reset button for about 10 sec, then release.
    It should boot into the backup BIOS now.

Method 3

Only use this if nothing else works.

    Short out pins 1 and 6 on the main BIOS chip by attaching a jumper to both the pins (pin #1 should be marked with a red dot or whatever)
    Tell a friend to press the power on button while you do this, because right now you are holding the jumper on the pins
    Remove the jumper you're holding between pins 1 and 6 as soon as you hear a beep.
    Backup BIOS should boot now.