BB Go 410 “Power on" then unusable. How to fix this?

I have a unit of BB Go 410 that when turned on says “Power on" then stop and unusable. If normal it should says “Power on, battery high/medium/low”, then usable (directly to music or anything else I'm listening to). I can still charge it and the lamp indicator can still show whether it's charging or full.

In my case usually if I leave it for hours it went back to normal and I can use it, but it keeps disconnected from my phone until eventually it went back to the previous state (“power on" then unusable). While in my wife case (a different but same type unit) every time we try to turn it on its always “Power on” then unusable.

Any suggestion to fix this issue?