Everything dies after turning key

OK the click and die sounds like you have a bad connection in the power feed. First I would get a new battery, modern batteries don't like to be left dead at all, and try to avoid using the vehicle to charge one that is that far discharged. Now as removing the cable reset the system, I would start by cleaning the cables at both ends, then check the body and chassis grounds for corrosion. Clean those as well. Now in theory a Jeep is supposed to be tough enough to run with the roof off in the rain, but they still have issues with the grounds like every other Chrysler product. Whet they do is take 5 wires or more, crimp a single ring terminal on the end and call it done, the problem is that moisture gets into the gaps between the wires and corrodes them, the connection can look perfect outside but be corroded enough that it doesn't actually work. On your Jeep the main grounds are from the battery to the engine block and from that same ground point to the interior systems. As such the battery and that ground would be the first stop. Then the battery positive to the starter motor and to the power distribution center main connection.

It is unfortunately a common theme with them once they start aging. Normally if you find one that is becoming an issue you will find others are as well. Typically I remove the bolt or nut, cut off the factory crimp and clean each wire than put 2 together and crimp them into a new ring terminal that has heat shrink with sealer on it. Then clean off the area, put them back together and then coat the spot with dielectric grease to keep the air out.