I missed the jumper cable being connected to the loader frame
I also see the batteries ground cable connected to the stud on the end of the starter motor
This was a know connection problem with Ford tractors due to corrosion between the stud and starter case
View attachment 82547
All my Ford tractors and the 555 have the ground cable moved to a starter mounting bolt
View attachment 82546
Notice the cable connected to the mounting bolt
Relocate the ground cable and I’m 95% certain that will fix the ground cable issue
As for your melted wires as I had said in your other thread the wiring harness on mine had been ripped to pieces
I reworked mine using a modified Ford wiring harness so unfortunately none of my wire colors will match yours