Logitech Ultimate Ears UE Boom bad battery symptoms

UE Boom was handed down to me. Original owner said it "stopped working".

Plug in micro-USB cable, and saw a white LED light up for one second. There has been no other reaction since. No smartphone has been able to discover the Boom.

I believe what happened did so suddenly. I am not sure if the Boom suffers from a dead battery or other problem.

I will continue to wiggle the USB cable, but I'm not expecting changes in behavior

What else should I examine if/when I take the Boom apart?