An evaluation of the returned unit has been 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 occurred in the lower battery pack between the cells and printed circuit board.There was blackening on the top of the lower battery pack and its printed circuit board (pcb).Cells 2 and 3 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.A recall is ongoing.(b)(4).
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