won't turn on but works when plugged into computer

I’ve tried reseting the player by holding the power switch but nothing happened. Any ideas what is the problem with my player?

Also when i disconnect it from my pc it shuts off

Other posts on same topic suggest a disconnected battery wire. If this is a new unit return it, else search for similar posts. I gather you can open it up and fix if you have confidence in this type of thing. If it’s a bad battery you can get a replacement, anything else and you might be out of luck.