My job charger 3 will not hold a charge and goes off after an hour on.

My job charger 3 will not hold a charge and goes off after an hour on.

I charged up jobless charger 3, turned on to play music when grandson takes a nap. Speaker turns of after an hour or so of playing. Reconnect to charge and lights indicate battery is full. When I turn it off, the battery indicator lights flash. What is the problem?

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