Did you try swapping J17 with another the same? Check M19, M21, M27 with the key on on both sides of the top of each fuse with a tester or test light. Sometimes you can look at a fuse and they look good, but check with a tester and it's bad.
Yup checked M19, M21, M27, with a multimeter they are all good. J17 checked out fine with a multimeter continuity check. I did try grounding the loose wire and somehow I suspect that is what caused the issue in the first place.
Have someone turn the key to start and you check the volts at the fuse box where the big cable is from the battery. Check volts before and when the key is in start position.
That's why I also had you do that, shows if you have bad cables or clamps. I hate to say this but i'm about out of ideas unless your TIPM is bad. Did you say you can here the starter relay clicking when you try to start the jeep? Did you try swapping the relay with another one that was the same?