They might just be stuck. It happened a few times on mine. The motor would try to start and then would pop an automatically resetting fuse and everything would stop.
I ultimately had to use the manual crank and force it to turn. Once I got past the first inch or two, the motor could do its thing. Once it was down, I lubed the hell out of the "worm screw" or whatever that cross-bar is called. Ran it up and down and sprayed dry lube on it liberally.
2018 Ram 3500 DRW/crew cab/long bed/4x4/4.10 gears pulling a 2017 Spartan 1245 by Prime Time
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| My family and I have fulltimed since June 2015