 point of connection, a solder point, whatever they've got inside of there, and it caught when it was under a load, it was just open. We'll see that a lot with car batteries. As the terminals corrode, you turn the switch on, you go to start it, it goes click, and all the lights go off, it's all dead, and then about a minute later, they all come back on, and you wiggle the cables and it starts. Same thing can happen internally inside of that battery.