Ответ на "iPhone5 - Black screen after swap, constant "bong" noise."I had the same problem. I replaced the screen on my daughter's phone. It would not power up but when I plugged it in, the bong noise came on regularly, and I still had a black screen. It was late so I went to bed. In the morning I put the two bottom set screws in and tried to power up again. Now I got the cable image, meaning the phone battery was dead and needed to be charged. I charged it and it all works. This leads me to two ideas. The bottom screws must both be in and must be contacting something to indicate to the phone that they are in place. I had only put one screw in the night before because I could only find one. I found the other when cleaning up before calling it a night. The other idea is that the phone went completely dead and this did some sort of reset. So now the phone works perfectly, and I hope this helps someone.