A. If it is a newly assembled battery pack, measuringthe voltage of each cell from the connecting pin between BMS and battery, and check whether the cable sequence is correct, or whether there is individual cable disconnected.
B.If the battery pack is abnormal after using for a period of time,check whether the screws are loose(the cable is crimped or screwed),or whether the socket connection between the cable and the protection board are loose. Also measure the voltage of each cell.( Some BMS do not support battery charge at 0V. Need each single cell above 1V so that it can be charged.)