Man I'd go through the whole harness end to end , if it's a chopped up mess then
I'd find another rather than drive yourself nutty trying to mess with it , but that's just me !

 

Sounds like the battery is good.

What I would do next is disconnect the battery and hook a continuity checker to the (+) and (-) terminals and see if you get continuity. If you do you have a problem. Disconnect the R/R and see if you still have continuity. If so you have a short.

Here is a helpful LINK.