Got this the other day from support out of Texas...and it worked!!

.  An issue has been identified with this model where if the battery drains to low it will appear dead and not power on.

1. Unplug the 40-pin connector from the tablet. If docked, unplug the tablet from the dock.
2. Press and hold the power button for 10-15 seconds (this performs a hard power off on the device in the event that it is locked or hung)
3. Plug the 40-pin connector back into the device. Let the unit charge for at least one hour (60 minutes) before pressing the power button. Pressing the power button before the unit is adequately charged will hang the device and prevent further charging.
4. After waiting for at least one hour, press the power button for 3-4 seconds to turn on the device.
5. If this resolves the issue, the battery was dead and the unit went into a hung state. A software update to permanently resolve this issue will be pushed via the Windows Update on ~Feb 12, 2013. 

Please let me know if the fix doesn't work.    Note that you must follow the steps exactly.  

The SW update that should permanently resolve this issue is expected to push over the air tomorrow.

Mine just did this and it's a 2004 model - that should be beyond an updateissue. But, this process did fix the issue. Just not impressed...