I clicked on the link and tried to look at the pictures. The load wheel icon just goes around and around and never loads the pictures. Maybe it's my ad block plus, but that's never happened. The pictures always show.
ETA: Nope, I disabled ad block plus and still can't see them. Shame ... I really wanted to see the insides of a Lavatube.
My guess is that the wires weren't large enough to hold the current. That doesn't make sense because it's supposed to be electronic control. The switch should only be controlling a small voltage that signals the electronics to turn on the MOSFET. There had to be some short circuit current coming from somewhere due to electronic failure or the battery voltage shorted through the switch to ground. It's also strange that it works and adjusts the voltage by touching the wires together after the fact.
I'd like to see a schematic.