When I am on a call, the screen automatically shuts off. When it does, it will not come back on no matter what button i press. For isntance if I call the cable company and put it on speaker, the screen will go off and when I am prompted to input selectons via the key pad, I cant because the screen wont come back on. If I get a spam call, I can't hang up because I answer and then there is no way to hang up besides pulling the battery. There is nothing in the way of the proximity sensor, any clue what is going on or how i can fix it?