I recently purchased this vehicle and it had the black screen. I have tried for 2 weeks to figure out what it was. I bought a used amp, didnt change anything. Bought a used hmi didnt change anything. Today I replaced the radio module with a used one, expecting that if it worked, I would get the theft locked screen. But instead, i got the display and everything seems to be working except i have no sound. I can see the volume slider go up and down but no sound. Can someone give me a clue as to what i need to try or do next? I would appreciate any help.