Lithium batteries unavoidably need a BMS to protect them from over and under voltage. Sadly, when this protection kicks in it will protect the battery totally cutting any and all power in/out of the battery.
As long as the Lithium cells aren't damaged, it's possible to bring back to life a battery that has protected itself either from over or under voltage.
Remove control board to get direct access to the naked and unprotected battery poles. Find the voltage, if it's too low charge it until the voltage reaches 13.5V, if the voltage is too high connect a 12v lamp to battery + and battery - to discharge it to 13.5V.
Afterwards we grab our eeprom programmer and flash the eeprom in the BMS board to its original "unlocked" data. File attached for reference make sure to only flash EEPROM!!
