I had a white iPhone 5 but decided I wanted a black one. I used a black body from an iCloud locked phone that I had and switched the motherboards. I starting having this problem the first time I turned the phone on. Knowing that the motherboard wasn't causing it, I switched both the home button and the dock connector out. It's been working perfectly so far. I'll comment if starts acting up again. Please email me at ozzy678@gmail.com if you have any questions. I work on iPhones.