Im no mechanic by any stretch but usually try to work on my own stuff. Maybe a bad Solenoid switch? Is is a Ford? I ask because I replace a couple of those on older Ford trucks. If you do find a Solenoid on the fire wall or fender you can jump post to post with a couple screwdrivers and it will crank IF thats the problem. I know some vehicles have the Solenoid on the starter.
Chevy z71
