It would be the orange wire going to the plug on the circuit board. There are times to male connector on the board comes off. That is where I would check. If the radio light works and dims with the headlight switch you know the orange wire has power . Your next place to check is the board. there is and easy fix for that if needed but the board would have to come out. I use a small machine screw and nut to replace the pin. Works every time and it will never break again.