I have been using iOS 7 betas without any issues. However, yesterday after the OTA, my iPhone 4 booted up with the Apple logo and then went black. iTunes is able to detect it and even when I tried calling on my number from another phone, the call went through but I didn't see anything on my iPhone. I tried restoring it by downloading the ipsw. I got the setup screen and after completing the setup, the iPhone again booted and went black. I then restored to 6.1.3, which worked fine. I tried to restore it again to beta 4, and same issue again. I doubt its a hardware issue, since I get the setup screen and it works. Any suggestions?