Look at
www.beckerautosound.com That is the USA division of Becker. Becker is a very reputable company and can repair your unit if you should choose to continue to use it. You'll have to track down the European info. There may be a repair shop in your area authorized by Becker.
But that doesn't answer the question of which component has failed. I don't know how I can help you out in that regard. An after market ( all in one head unit ) system in this car is a major problem due to the amount of re-wiring necessary. Essentially, you just abandon all the original wiring intact and run new wires to all the new gear. Good Luck. Tod