Since I added ios update 7.0.3 tonight, my iPhone continually cycles off. It comes on for about 1 minute when I can open it, enter my iphone security code, open my emails, but then the screen goes black and after a further minute the apple logo appears - this stays on screen for about two minutes, then the on screen comes on and the cycle starts over again. Never had this problem with updates before. I have an iPhone 4 HELP! What should I do?