Man, that's hard to say... but it sure sounds like you had a circuit breaker jumping on and off rapidly, and then finally, the fusible link let go.
Now, WHERE that link is on a class A? OMG, I have no idea...
but, I would trace the heavy battery leads from the engine battery, the positive one, and it likely has some tie point with at least one or two other smaller wires connecting to it. This is likely a relay, but could also be at the starter solenoid.
Between one and all of these wires will ahve a section of flexible wire attached to it and if burned out, may actually look melted or even open the wire to the air, exposed.
This is likely where you lost power at.
Other options would be burned out ground wire or wires that run between the battery and chassis ground and your wiring harness inside.
Well, I know there's more possibilities, but that seems a likely option.
