Cerba, dal topic di DooMLoRD direttamente direttamente da XDA:
while device is power ON
Volume Up + POWER (for 10 seconds) -> resets the battery, its like removing the battery and putting it back in [device will vibrate once]
Volume Up + POWER (for additional 5 seconds, total 15 seconds) -> will power off hard, device will power down [device will vibrate thrice]
Prova così...altrimenti credo tu debba flashare il kernel (o addirittura il firmware)...