I've recently replaced an iPhone 5 screen but the phone won't turn on. If I plug the charger in it comes up with the apple logo, which then after a few seconds disappears then comes back over and over again. I've tried holding the power button and home button at the same time and I can get it to come up with the iTunes connect logo but that's as far as I can go. If i unplug the charger the phones goes blank again. I've also tried plugging it into I tunes but the computer doesn't detect it. Someone please help???