i was en counting the same problem with my g2 i search all over the internet but i could find an solution,then i decided to try on my own,this what i did to disable the proxy sensor
1 open the back cover of your phone
2 locate the proxy sensor plug , is on the right from the front camera when the phone is facing down
3 remove the whole sensor and hold it and make sure is upright the plug must face down
4 there are two little sensor on left and right, break the sensor which is on your left with a side cutter make sure you dont destroy the other sensor or the circuit board
5 put everything together an problem solved,no more blank screen,no more screen shut off when unlocking on the dark