The unit was returned and an evaluation completed.Upon visual inspection it appears that a thermal event occurred.It is 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 upper battery pack between the cells and pcb.There was a blackening on the top of the upper battery pack and its printed circuit board (pcb).Cells 5 and 6 appear 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.This concludes the investigation.
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