Xperia Z2 :: Software Update Failed - Try To Turn Off To Charge

I have installed Lollipop but PC Companion insist an update exist i ended with a Software update failed boot message, my error was try to update with battery with 65% of charge. And cannot remember what happen but i ended with the Software update failed error, and the phone switch off and on and off and on with the same message, i read other post about turn off and charge, but i turn off with the little red button to force it but if i connect the magnetic cable or the usb cable to power it turn on again, i force to turn off and and the phone turn on again (with the message of failed update).