Here is the problem:
1st: I bought a used Vw phatbox with vw cable and soft, I then bought a audi cable and upgraded the firmware to the latest one
But when I plug the thing into the car; everything goes as it should first hand, the firmware upgrade is done and both light goes off
but when I try to start the thing (going on changer mode on the radio) it doesn't prompt me anything, just behave like a normal cd changer, I can change disk and choose track, but there's no sound coming out of it and no playing message
Is my box a defec one or it is something I do or did wrong?
By the way car is a 01 TT with audi concert cassette player