I installed an app to help test the proximity sensor because when I'm on a call the screen will turn off like it's supposed to but then won't turn on without me pressing a button. The results of the test are that the sensor is active and when I hold my hand over the phone it detects the change. But when I take my hand away it won't detect that it's moved. I did a reboot and factory reset and neither worked. Then I did a battery pull and it worked for a day. Now it's broken again. Any thoughts?