EP53 :: Disaster at the muffler shop has me 'Exhausted'

This is the 53rd episode of the ongoing project to rebuild a Jeep Cherokee XJ for my 17 year old daughter.
Our goal to get this jeep ready for Senior Semi-formal so my daughter can drive it to her school formal. this stage was ready to get it to the muffler shop and have a new exhaust put on. but sadly something went wrong and the 25 year old jeep showed us again that we should just buy new parts instead of trying to re-use ones that are old and can cause us problems.
But something strange happened here. I can't explain why this would have broken by just being put in a parking lot for a while...
headlights can be found here: amzn.to/4cNsOFt
Raptor Liner kit amzn.to/4a6y0CA
The OTC puller you can get here : amzn.to/3IGEv36
the OEM puller you can get here : amzn.to/4aiRDab
The XJ hatch bumpers can be found here : amzn.to/3UxsS5P
The XJ Hatch Seal can be found here : amzn.to/3UrpWYn
seal kit :: amzn.to/3UVLNr0
The Xj Coolant reservoir can be found here : amzn.to/3HNc0Aq
The scanner I used Affiliate link - amzn.to/3OlQC8K
and some other auto options - amzn.to/496hHWd
rail cover kit: amzn.to/3TEqdGZ (affiliate link)
The affiliate link for the bleeder kit we used to bleed the brakes.
amzn.to/4auobz9
misc - other
amzn.to/3QK0Hgd
amzn.to/3MSzyGN
amzn.to/3R9X4BW
amzn.to/48W4eQK