Possibly sleep/wake button problem. (Black screen)
I have replaced the screen on a friends iPhone 4s.
The screen works fine at first when I turn it on, but after the screen goes black by itself or I push the sleep/wake button to make the phone sleep, it wont come back on.
(screen comes back on if I wait a while, but only once, then I have to wait some more)
I can see a little back light going on and of as I push the sleep/wake button, but nothing more.
I can turn it of without seeing and back on again and then it works fine until I push sleep/wake button or it times out and sleeps automatically.
Anyone had this?