I just had that happen to me today as a matter of fact. I was using Calibre and when I ejected the Kindle it stayed in the USB mode and wouldn't do anything. I held the power button all the way for about 20-30 seconds and nothing. I plugged it back into the socket plug, held the button again and after about a minute or so it rebooted and it is fine now. scared that I would have to call customer service and get a new one. Hope that the tips that other users gave you worked for you
