Not sure if this will work for anyone else, but it worked for me...
Issue: Rebooting Apple Watch would bring up watchOS 2 beta (I could see TimeTravel mode and Nightstand mode) for less than a minute before the watch went back to showing the upgrade ring, which would stop at the 2nd or 3rd second.
Solution: After trying multiple reboots (and leaving it going over night) with no success, I finally turned off all 3rd party apps in the iPhone Watch app and then Unpaired the watch (again from the iPhone app). Another reboot of the watch (holding both watch buttons down) and it finally got past the 2nd or 3rd second and fnished upgrading as a new watch. I then had to re-pair the iPhone and Watch again once the upgrade was complete.