Jeep died

First, if you have a check engine light on, you should have the computer scanned for codes. If there are any, send them to me.

Next, your engine could've died from several different reasons. Ignition, fuel, loss of compression, failed computer/sensors. And when you say "doesn't turn over", did you mean the starter no longer works either?

To check a no start, you first need to make sure voltage is getting to the starter via the ignition key. If yes, but the starter won't turn, then it needs to be replaced.

If starter does turn, then you need to first check for spark at the plug. If none, you diagnose the ignition system until you isolate the reason why. If yes, move on to fuel at injectors and repeat the diagnosis.