Strange Electrical Glitch

[SMarquez]

My son's 95 Astro died on him a few days ago. It just quit altogether. The interior lights, headlights and accessories all quit. I can't hear the fuel pump either when I turn the ignition to on. The starter cranks but won't start. Maybe a coincidence but he also shorted the trailer wires by them dragging on the ground, It seems like 1 whole circuit is out. I pulled the 4 wire plug behind the battery with the fusible links. They all seem to be intact but 1 pin in the plug looks slightly melted. Any ideas?????