I think the OP left with his Scout troop already. Hope he found the problem.
I still hope he checked the batteries for corroded connections first, before proceding with further troubleshooting. This is a very common problem with a camper that has been sitting up for a while. I've seen many times when someone assumes the battery connections are good because they stuck their meter probes to the terminals and saw voltage. This doesn't take into consideration the battery connection itself and can lead their troubleshooting astray.
