I am pretty certain the modules were not flooded, and the desiccant pouches went through a big screwed in plug into a little plastic cradle inside. It seems that the pack was engineered to be kept at low RH.
Once I took the modules out, they went on a pallet on the floor of my shop, covered in a sheet of plastic. The space is left open to the elements, so although the modules were 30 feet from the outdoors, if the temperature swings sometimes the whole floor in there will get slick with condensation. The BMS wires were copper, and ultrasonically welded to the aluminum bus plates - and it was those connections that failed. I am not sure if the Model S used that system, or if they are even accessible to inpect - the modules I have do not have a sealed plastic case aroud them, they are just wrapped in insulating plastic. Anyway, my modules are pretty rare, and I have not heard of anyone else that has had similar problems, so hopefully it was just a fluke.