Default [Q] samsung GT-p6800 not booting up

after official ICS upgrade to my samsung GT-p6800 , power button is not working for booting up the system. So when i did the reset to factory reset the device restarted but stuck in recovery mode but i cannot select any option because power button is not working. though i can scroll through the option using volume buttons.
Experts help me how to get back my system. Though i have the firware backup.

thanks in advance