I am thinking that the blown fuse caused the "loop" to be broken. Maybe the charger didn't know that the battery was fully charged, and kept pushing juice without slowing down. And maybe if the fuse wasn't blown, it would have figured out it could have stopped pushing a charge.
Kinda like a breaker pops off when something grounds out or the circuit is overloaded. Maybe that fuse would normally prevent too much juice from going to the battery. After I installed a new battery, I then replaced the fuse. If it popped again, then I would have known the problem was somewhere back up the line. But thankfully it didn't.