Connect the electrical cable of the mirror

I do not know the color scheme and I have not encountered 4 cores in practice either

Are you abroad? Maybe black is a 2nd phase that is connected directly without a switch. Then yellow and beige/white would have to be the correct ones for blue/brown. Otherwise, if it doesn’t work like in the photo, just try swapping blue/brown. Otherwise, you would have to remove the switch from the wall and take a look inside....

I might maybe get an electrician, HE then opens the switch and looks... or do you also install your brake on the car yourself, following instructions from a forum like "Yeah, just turn that part around, then it might work"...

I might get an electrician, HE then opens the switch and takes a look... or do you also install your brake on the car yourself, following instructions from a forum like "Yeah, just turn the part around, then it might work"...

Do you really think an electrician would come for that?

Normally, connecting lamps is not rocket science. The cable colors are standardized, so blue to blue, etc. And if you still mess something up, the RCD just trips ;) This is not comparable to the brakes on a car, at best to the brakes on a bicycle. And most people change those themselves. In this case, however, it would certainly be helpful to know where the OP is located and from which period the electrical system dates.

You seriously believe that an electrician will come for that?

As a family with a craftsman illiteracy who was recently in the same situation, I can confirm your impression: unfortunately, electricians do not stand at the next street corner with "will cable for food" signs. We had collected and had several lamps and minor electrical work, and even for that, no electrician could be found. In the end, we found a small moving company that helped us for a few hours, and they took care of it.