One more thing: in the earlier models (x250), the image from the factory installed reverse camera was displayed on a screen hanging of the roof like described and shown
here.
I don't know which year they started installing a radio unit with reverse camera display on the dashboard. Was it with the introduction of the x290 model (2014) or one of the faceliftings? Were all radio units able to display the reverse camera image? Or you needed a special model?
Looking at both
stickers above and connection diagrams on them, it seems to me that neither of them has a connection to the reverse camera. Or it is not clearly described.