komatsu pc40-7 wiring

ok folks here is what i got. komatsu pc40-7 battery started going dead figured it needed a battery put the jump box on it to start it to finish job.i was not there but my help said the builder wanted to move it. when my helper came around the house the jump box was hooked up backwards he switched it it started but the controls would not work and it would not shut off.we got it back to the shop the starter has been screwing up so i started there it checked out just needed a clutch.next was altenator guy said it had a dead short in it. put everything back on everything is good except still no controls.pulled the seat out of it when you push safety switch it arcs and fuse starts smoking but doesnt blow the way the switch looks to me it should be a ground circuit but i dont know that any ideas ???