That’s Good News!
Loss of continuity between the battery negative and the Green/Black wire is what you want, it shows that you have found where the wire was shorting to ground and the cause of your fuse blowing.
looks like Mike O was right all along at the site of the problem.
I suspect that the insulation has just worn away exposing the copper conductor which has short circuit to earth. Have a good look at the copper wire to make sure it hasn’t partially burn through which would reduce the current that that wire could safely carry. If the copper is damaged, you may have to splice it or bridge the damage wire with solder before insulating it.
Once done just add some extra protection to the area to prevent further chaffing.
When you come to re-wrapping the loom, make sure that at the ends of the loom the wrapping is as tight as you can get it to help prevent water getting inside the loom.
Well done !
