In the box there are two packs, each one with a BMS board.
if one cell voltage is out of range, the general switch disconnects the output,
and battery stays offline, because of the five pins chip at each cell, that give command to turn off the protection field effect transistor.
Measure each voltage of cells and visualize the defective one, replace defective cell,
don't try to resurrect cells, will work few time and get back to failure, replace them! after this battery output protection switch will be "ON", battery is back to life.
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