It updated, rebooted...
Booted up, showed the loading progress bar... then said it needed to reboot
After ~15 minutes sitting there I pulled the power... it came back up to the progress bar, then said it was rebooting again...
Same exact thing... so it's in a loop where it thinks it needs to reboot.
Kris - for S&G, go to the Diagnostic Port (8081) and do a Soft Reset. There is a possibility that the reboot is caused by a database issue that will be fixed by a Soft Reset.
Another possibility is that the power supply is flaky - and it would be worthwhile trying a different power supply (5VDC, >=1A).