I did not discharge at all. More to the story, though.
P-group voltage was all 4.08V exactly. Loop key was still in and metr/vx2/escapes all on drawing power. I assumed it had got to cut off voltage and not restarted when voltage dropped. It was 48.9 at last check when the charger would not kick on.
I just went to check voltage drop overnight. It was only around .2V. I decided to check the charger again and it’s working. I haven’t moved a single wire since last time I checked. Really stumped now. I could believe a bad solder joint, but it’s not even been breathed on since last check.