Sabre ubrubtly shut down, and will not restart

Ok, I have a Sabre lawn tractor with the 18hp intek vtwin. I was mowing the lawn one day and all of a sudden it quit running. I thought I ran out of gas, but no.
Now, I have been starting my lawn mower by bi-passing the starter switch. My positive battery cable at the battery is corroded and wont get a good connection. I haven't got around to replacing it. So I would just jump the starter with a jumper cable from the positive terminal to the starter.
now that we got that out of the way. The tractor was not out of gas. I checked the oil, and it was a bit low. I put oil in it. Wentto jump start it, it cranked over but would not fire, but immediately smoke came pouring from the front of the engine. Smelt like electrical. Sure enough, a ground wire fried on the front of the engine. I have no clue what it is. Fuel shut off switch? It's on the bottom of the carb. I sprayed carb cleaner in the air cleaner to see if it would fire up. It fired up immediately with more electrical smoke, I heard a bad knock during the 2 seconds it was running. I also noticed some oil leaking from the left side of the engine.I have had nothing but problems with this sabre, but never the briggs engine. It looks terminal, but who knows, maybe it's an easy fix? help is appreciated! Thanks