Help Lollipop - No sound from speakers when unplugging battery charger


I'm actually facing a big problem with my phone which is a low cost phone probably unknown ECHO Smart Mini. I'm running Android Lollipop in it.

The problem is that no sound is coming out from the phone speakers (no ringtones sounds, no media apps sounds) until I plug in back the battery charger and everything come back to normal. Also every sounds are working in the headphones when I plug in them. And when I unplug headphones the icon from headphones dissapear as it should so It's not a problem with that I guess.

I have already tried factory reset.

Any help ? Thank you :)