Appreciate the helpful input here!!

I ran a fan overnight after pulling up the carpet. More of an observation but that giant bundle of wire below the fuse box in the trunk runs right under that door, so the same errors when that is flooded are found here probably, and consistent with my experience.

I also found my battery voltage quite dead, around 11.9-12.0. charged overnight as I think that can also cause gremlins.

Started the truck this morning, still definitely some humidity and some errors. Blasted the AC out of the rear vents for 30 minutes and boom, zero DME errors and the iDrive screen finally stopped blinking. I think it helps that when the b pillar vents are closed it blows under the carpet (by design!? Nah..)

I’m guessing just a slow leak through that carpet can cause this headache of an issue.

I pulled the door card off and, not surprising, the vapor barrier basically came with it. Butyl tape arrives Thursday.

Going to button back up probably this weekend and pray this solves it.

Good luck wonton.

Edit: I should add it effing poured yesterday which probably lead me to finding the water.