I am trying to troubleshoot a starting/cranking problem on my dad's Craftsman GT5000 with a Kohler Pro 25 HP V-Twin engine. My dad changed the oil and tried to start the mower. It had been setting for some time and barely cranked. My dad then boosted it with his pickup truck to start because he said he had done it before. When I went over to see what he was doing, I noticed the booster cables were hooked up reversed. I corrected them and tried to start it, nothing cranked at all now. I removed the battery and fully charged it, then installed back in the mower but nothing cranked. I jumped the starter solenoid terminals and the engine cranked fine but did not start or fire. In looking things over, I noticed the wire at the carb/air cleaner linking to what I believe is a fuel pump was disconnected, so I reconnected it. I asked my dad if it ran good, and he said it hadn't been running good, so I am thinking the disconnected fuel pump wire might have been the cause. With all that said, my thoughts are that a fuse or other electronic device became damaged due to my dad having the booster cables connected backwards. I am mechanically inclined but not experienced with this mower and the electricals. Does anyone have suggestions on fuse location, if applicable, and other electrical components that would likely have been damaged from the improper booting hookup?