The Sansa Clip 2.01.16 has probably some bug concerning running out of battery power. When forgot to close my Clip it was not poosible to restart it, I pluged it to computer USB, not working. Did the same thing with the USB charger put it there for about 24 hours, still not worked. Okey, honestly the next day I was going to the tray and throw it away, but by any reason I tried once more and the thing was working!
If your Clip does not work with USB when it has ran out of power, wait at least 24 hour disconnected. Try to start it and if the Clip starts: plug it immidiately to the usb charger or computer. My theory is that if the battery is unpowered a day or two you can start the on-procedure.
I have now updated it to 2.01.32 and hopefully it will work for a long time!