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Check the obvious first.
Check the ground connection where the cable connects to the frame.
Check connection of the battery plus lead at the starter.
Find the fuse box and check all main fuses. Some tractors have main fuses close to the battery positive lead.
Could also be ignition switch.
If you are on good terms with your dealer, ask if he could get you a copy of the wiring diagram or buy a service manual.
I would recheck all the fuses and check the starter relay. If there was 36 volts put to it there is a chance the fuel shut off solenoid might be bad, I can't remember if there is a relay before it or just a fuse, but if you get it cranking and it won't fire that is most likely your problem.