Electrical Short - What Just Happened?!

You are welcome. Learning to do some simple tests will save you money in the long run. "Sometimes" throwing money at it makes sense. Let's say, maybe it's the connections, but the battery is 5 years old anyway. Maybe you would not feel so bad if you "threw" a new battery in and that wasn't really the problem.

As an old guy (67) I've been fooled a few times by "appearance" connections. About three years ago, my 86 Ranger would not start. The cables looked GREAT!! But down where the ground cable tapped off to hook to the frame, and went on to the engine block, it was all corroded inside the cable jacket. A few voltmeter tests soon showed up "where this had" to be.