I had the same "not working and started working again" experience.
My main complaint is that the droid nor the lightsaber come with any instructions of how to fix,troubleshoot, etc.
When we were leaving DHS (literarlly a few hours after building it and carrying it around all morning) .. we got to the car and I heard it make a electronic noise .. thinking that was odd and maybe bumping it on, I opened it and switched it on .. NOTHING. I panicked! Batteries can't be dead already. The metal pieces were loose so I took the bottoms off .. put them back on .. checked things .. nothing.
So . I proceeded to march back to the park while my family was going to go back to the hotel. Halfway back to the front entrance I heard the lightsaber make that "beep" again. Huh? I opened the case pulled it out .. turned it on .. and it was working? Wuh?
Do these have a sleep mode or something?
Our droid was the same thing .. was working fine at the hotel. We travel back home .. take it out of the box and the remote turns on, but the droid doesn't move. I opened the droid up (bb-8) .. checked the batteries -- flipped the switch off and on again and even hit the pairing button and voila .. it started working again. It was like it was in sleep mode or something as well.
Is there more detailed documentation for these things online?