I have bought one of these mmi boxes that allow to have AA and carplay without changing the screen but I am struggling with the installation. I think I have followed the instructions perfectly but when I installed it iDrive worked fine but when I hold back button for 3 sec I am getting a black screen that I can quit by switching back to Idrive. Do you think that I am unlucky and that I got a defective box or that I am doing the installation wrong. I would like to get your feedback and experience about these retrofit box. Thanks