Did you try a soft reboot at any point? Hold the power switch in the off position for 20 seconds or so, then let go and try to turn it on. Does the Fuze show up as a drive when you connect it to your computer? If so, you could also try reinstalling the firmware following the instructions here:
http://forums.sandisk.com/sansa/board/message?board.id=sansafuse&thread.id=23276
