Several times now my screen has gone black and cannot be turned on. The first time I got it to work after pulling the battery a couple times and inadvertently put it in safe mode. I uninstalled the apps i had recently installed and the phone worked fine. It did it again today. Couldn't turn it on after using it all morning. The lights work and I can hear the sounds but no screen. I pulled the battery several times and nothing so I just left it alone for about an hour, and then it worked. But, the swiftkey app. Is no longer my keyboard. (I hate the stock keyboard). I don't know if that app is the problem, I kind of doubt it because the screen went black while I was typing this with the stock keyboard, or if another app. Is causing it or if my phone is defective. I have not dropped it or gotten it wet. Any ideas?