No mute button. You start the car with the radio off and it will not produce volume until you re-start the car. Have not tried the nav but all other display functions work. Thanks!
Some clarification. The car is running. the radio/CD is on and it works fine. You shut the car off. It does not work. Do You put the ignition/key in the accessory position? Or, the car has been running. You never turned on the radio/CD while it was running. You turn off the car. If you then go to turn on the radio/CD it won't play. Did you turn the ignition/key to the accessory position? You say the volume level registers and the nav. screen also lights up. Can you use the nav. screen?
Does you year and model have a mute button on the steering wheel or head unit?