I tried to install Android 4.4 KitKat and i ruined everything. Now the screen is, and stays, black and it can't Turn on. No matter how long i press the Power Button. I can't access the Download nor the Recovery Mode. When i connect to my laptop appears " qhsusb_bulk " , nothing further ( what can i do ? http://s7.postimg.org/54pfaqrwb/Capture.jpg