That looks like one of those Chinese "no information available/too cheap to repair" devices. Unless you can open it and diagnose the cause of the problem yourself, it's going to cost you more to get it fixed than to get it replaced. (Or you can replace it with a name-brand device that you can get information about.)
I'd diagnose a bad charging port connection and/or a dead battery, but that's just an educated guess, which is all I can do without having the device to test.