I'm going to be honest with you, it doesn't sound like you are up to the challenge of figuring this out yourself, based on your description. You should probably take it to a mechanic.
Feel free to prove me wrong, but I'm guessing you didn't even change the battery yourself because if you had, you would have seen that there is a second battery right next to the primary battery. Both batteries have to be healthy for stop/start to work. Now I have no idea how you could possibly have killed TWO batteries on a 2019 model, aka brand new batteries, but Jeep does use the worst cheapest most horrible batteries of anyone anywhere so I guess I can swallow that horse pill.
My advice would be to get yourself one of these battery chargers: https://www.amazon.com/dp/B07SQTF1FB...v_ov_lig_dp_it
That particular charger has a screen on it and can double as a bargain-bin voltmeter. What that means is when the charger is not plugged into the wall it can tell you the voltage of your batteries. This saves you from having to buy a voltmeter. Ok, so with that charger you can check your aux (2nd) battery and see if its voltage is at least 10.5 volts. If its much lower than that, you may not be able to save it, but you can try by using that charger. The charger has a pulse-repair mode that can try
to desulfate the battery. Might work, might not, depends on what is really wrong with that battery. Then the charger can also do its main function and try to bring that battery to a full charge.
Maybe with a pulse repair and/or a full charge the auxiliary battery will come back to life and stay working. Be aware, the issue may come back later if the battery was not the primary reason for the issues. If the IBS has failed or is faulty then the auxilary battery will never be properly charged and eventually give you problems again. At that point it is probably for sure above your head to fix.
So, to recap, you can try a small inexpensive charger to check the approximate health of the aux battery and charge it up. Thats the cheapest easiest thing you can try on your own. If you still have issues after that, have a parts store put their battery tester on and confirm the aux battery isn't just shot with a bad cell or something. After that, suspect the IBS module at which point you will probably want a mechanic or dealership to work on that. Using the charger may mask/hide the problem, don't be reliant on that, its not normal to have to charge your battery all the time.
One exception to that: If you leave the car parked for long period of time, you should have a battery maintainer on both batteries to keep them topped off. Each battery must have its own maintainer. It must be fully automatic. That one I linked above would probably be OK but I don't know if I would trust it for days and days unattended, maybe go name-brand at that point. These cars have electronics that NEVER shut off, so if you leave the car parked the battery runs down which is bad for the health of the battery and will give you electrical problems even if it starts up. Something like this would be good (two of them): https://www.amazon.com/Schumacher-SC...s%2C175&sr=8-4
If you can't park it near an outlet... absolute last resort would be some kind of solar maintainer. Those are pretty unreliable, mainly because the sun is unreliable, and if you cheap out then they will drain your batteries more than charge them. Again, you have to have one PER EACH battery. The cigarette lighter option will not work because the cigarette lighter port doesn't stay connected to battery (at least, not the front one, and the rear one will only connect to one of the batteries, so just hardwire both).
As you can see, as simple as a 12v battery may be there are two of them here in a complicated system so try to learn about it if you can to head off these issues.