Getting back to this topic and finally about to order the Chinese made remote key fob from Ebay as advised to see if the problem is in the key or the car itself.
Not sure if I'm mistaken, but if I would order a remote key fob like this:
https://www.ebay.com/itm/274720812901 and proceed with the typical programming operation by putting the key blade into the ignition, isn't there some kind of a theft protection which detects if something unsuitable if inserted into the ignition switch and then make it impossible to start the car afterwards? At least I recall there was something similar to this in the door lock of the E53. Or should the blank key blade be safe to use in the ignition?