You're going to have to better describe what it does and/or doesn't do.
I understand it doesn't start, does it turn over? fast, slow, normal?
What is the battery voltage(s)?
What was it's condition when it died? idle, driving down the road, trail, high angle,water, etc.
You're positive it has fuel? Positive?
Is the bottom of the fuel tank damaged causing a false reading or prohibiting fuel pick up? Is anything hanging under the vehicle, hose, etc.?
There is a set of high amp fuses in the TIPM that is closest to the engine. If someone tells you you need a new TIPM check these first.
Just disconnecting the positive and negative battery cable does not power down a JL/JT. There is a ground lug on the passenger side fender liner located between the Battery and TIPM , this has to be disconnected to power the system down completely (and despite it being a ground it will spark when you reconnect it)
Using your thumb push all fuses home in the TIPM, make sure they are all seated fully (not a single fuse was fully seated in my new Power Wagon).
Probably late to the game, but good luck