Hi, I just got one Yuandao N12, it has two usb ports, 7" screen and so on. I think it had android ice cream sandwich. The thing is that I played around with it for about an hour, the battery had about 80% when I started playing. While looking through a pdf file the screen froze while I was adjusting the screen brightness. I hold down the power button to shut it down and it hasn't started since. Nothing happens when I plug it in to the computer with USB cable. Nothing happens while I load it. (which polarity does the DC charge have btw?) Pressing down the power button you can sometimes see the screen get "black" and it shuts down as soon as I stop holding down the power button. Does anyone know any tricks, button combinations that will help, firmware or something? Since nothing shows up when I plug it into the computer I can't really use any of the software from this site?