The charger is supposed to have reverse polarity protection, and I guess to some extent it does as it didn't attempt to charge the cell. I'm guessing that being installed backwards put some sort of parasitic draw on the battery and it just sapped the juice from it as it sat there. That said, I've noticed that the charger sometimes emits an extremely high pitched whine when the room is cold, sort of like an old crt tv. Also, it says Efest on it and the Bluetooth functionality is worthless, so I may drop-kick it into the street and pick up an xtar or maybe a balanced 18650 sled for my Hitec hobby charger.
In the end it was my fault, but still a gut punch as these cells were just a couple of months old and were performing really, really well. Also, it was one of a matched pair, so now I have a single cell and basically nothing to use it in as the only single cell mods that I have left are mech tubes that have been shelved for years. Guess I need another mod now, lol.
Did I mention that I had to order the 20s' in to Canada from Lightning Vape in Florida because everyone else bends us over ridiculously on shipping? Did I mention that Canada Post has been on strike and the eta for packages is now April 2019? (Still waiting on shit to arrive that I ordered in effing October.)
Grrr.