Just repaired a Lenovo A2 charging port. After the repair when I got the tablet to charge the touch would not work. I held the power button down for about 15 seconds until it powered off. A minute later I turned it on and it reset itself and the screen started working. I knew their was nothing wrong with the touch screen because the cable was not damaged and after testing the connector on the board for current I got a reading over 2.0 volts. Hope this helps.