hello I know that this post is a little old now, but i found a fix that helped me alot. firstly you disconnect the ribboncable to the screen and the ribbon cable to the sd card slot. after that you should just keep it charging for about 5 minutes, and then hold down the startbutton. after you hear the boot sound, you can connect the ribboncables again, and let it charge some more. (P.S. I dont know if this works for you, but it worked for me on 2 tablets which had the same problem).