Battery becoming very hot
We're getting to a point where there are two ways to figure out wire connections. One will be with a continuity using a multimeter, the other by unwrapping the tape holding the bundles. Are you up to tackling either one?
There's no fuse on these wires (other than the link) so this isn't the sort of diagnosing or repair where we can just try moving wires and see if it works. The battery carries quite a wallop. We want to be sure of what things connect to.
And the second part is whether you're up to doing some wire work?
Its going to involve some crimping, new terminals and maybe some new wire.