Even after the 2nd visit the problem unfortunately remains. Strangely enough the car did not connect to the Mercedes Benz Star diagnostic nor did with the Chrysler diagnostic machine. It did connect through a normal laptop running a Mercedes diagnostic and the exact words of the mechanic were that there is a battery short-circuit on the airbag module sensor. He reseted the indicator (cyclespin) 3 times and he also concluded that most probably the airbag sensor module has to be replaced....

As soon as i figure out how to safely remove the automatic gearbox center console, I am going to remove the shortcircuited module and send it to a car electrician before purchasing an Ebay used one. Will update this thread with any news.

P.S. The mechanic informed me that no VIN programming is needed for this module , however it is possible that the 2nd hand sensor might need to be configurated through a Mercedes tool that only exists in dealerships (Greece).