"iPhone 4S display black and constant vibrating (sounds) when charging?"に関する回答I have same issue. But I could turn on display just by using power button + home button . Try this: press power button + home button for 5 sec then just release and again press power button + home button for 5 sec. Do this 4-5 times you may get apple symbol in screen. I started facing this issue after ios 8 update. So I think its not hardware related.