Did some more testing:
1. Cheap transformer based charger probably destroyed the BMS. I measured max voltage at charger output with my scope this morning and I was reading 72V. Average was 36V. Yikes!
2. It is a 15S pack, not a 16S pack. Bms can be used for 15 or 16 cell configurations. Voltage that cells settled to was lower than typical for this reason. I am kicking myself for not noticing this.
Summary: don't use cheap transformer based chargers. I rarely test 48V packs so did not see the need to buy an expensive charger. I was wrong. $1,699 battery is now a brick. Oops