Upon visual inspection, it appeared that a thermal event occurred.It was not possible to determine the exact sequence of events that led to the thermal event.However, there is evidence that a short occured in the lower battery pack between the cells and printed circuit board.There was a blackening on the top of the lower battery pack and its printed circuit board.Cells 2 and 3 appeared to have been involved in the thermal event, likely by supplying energy into a fault in the board.Additionally there was a slight melting of the handset plastic enclosure.The unit was repaired and returned to customer.This concludes the investigation.
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