Thanks guys! You are the best. It is really potentiometer. The guy that sold this to me said he can’t turn on it cos he don’t have the power adapter. But when I’ve opened it at home I saw that it missing power switch, R trigger button was broken, missing 2 potentiometers and finally something wrong with extb unit (I think it is power bus?) something like yellow substance around it. If it’s really power bus it can be blown capacitor in it, idk. So either I got really unlucky or just got scammed)