The issue is often looked over by repair shops or people repairing their own G2. There is a black rubber gasket that goes over the proximity sensor. If this is left off, then your screen will go black and stay black until the phone call is over. The reason I know, is because Ive had this issue before and I realized I left the black rubber gasket in the old frame. Once I transferred it to the new frame, the proximity sensor worked properly.