If none of this works then you probably have a hardware issue, sometimes taking every thing apart and only plugging in the Power-Volume buttons and Digitizer can help find the faulty part unless that happens to be the screen/Motherboard itself.
If none of this works then you probably have a hardware issue, sometimes taking every thing apart and only plugging in the Power-Volume buttons and Digitizer can help find the faulty part unless that happens to be the screen/Motherboard itself.