Default [Q] Updated samsung galaxy mega SGH-i527 and the touchscreen is no longer responsive.

Is there a way to downgrade the firmware, or way to flash a different rom onto the phone so i can use the touchscreen again?

I do NOT have USB debugging mode on ( dammit ) so is there anyway to turn it on with my current situation? I restored the phone to factory condition and everything so i cant even hit next to set up the phone.