The battery pack was received back from the patient with mechanical damage.The cover of battery pack, with lot code information, was missing.Investigation revealed extensive water damage to the battery pcm (protective circuit module).The water acted as an electrical current conductor allowing the current from the battery to bypass the protection circuitry and the energy stored in the battery was released momentarily.It was concluded that the battery pack was subjected to an impact, sufficient to break the ultrasonic weld and detach the battery cover.The damaged battery pack was subsequently placed on a surface with enough water present to seep across both sides of the pcm.This caused several components on the pcm pwa to short and overheat.
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