BQ78350-R1: Individual cell discharged

Hi David,
The bq76930 does not turn on or off cell balance by itself. The bq78350 does limited balancing according to its algorithm. If it is balancing and sees a cell go to low voltage it should turn off balancing and turn off the bq76930 which would also turn off balancing. Loss of communication between the bq76930 and bq78350 during balancing could leave the selected balancing on, but the system should continue to operate and likely drain all cells to VSHUT (< 3.2V/cell). Cells discharged to 0 would seem more likely from some defect or damage on the board. Look for resistive damage on the bq76930 inputs, leaking capacitors or contamination on the board. You should be able to see current as voltage across the input resistors, then it becomes more difficult to determine if it is into the IC, the capacitor or some other path. If you have opened the electronics pack to access the circuit (which is normal), try to load the board with the same mechanical torque and electrical bias as it experiences when in the system while looking for the currents. Looking for patterns in the discharged cells may be helpful. If the circuit is not showing a fault it has either cleared, was behaviorial which is unexpected, or may be outside the board. If you have it enabled, looking at the lifetime data from the bq78350-R1 may be informative. If you have access to packs which are not operating due to UV but cells have not gone to 0V, those may show some different clues also.
I can't think of other suggestions at this point so I'm selecting "thinks resolved" although I realize your problem certainly is not. Please reply with what you find or with other questions. Your response may be helpful to other community members, and some may have other suggestions also.