The spinning of the fuses is to clean the connections at the tip of the fuses ...Benz fuses are notorious for making bad connections at the connection ends, specially after sitting for long periods. You should do them all.

If there is a poor connection there, the inerlock relay gets no power and on the factory alarmed systems, the relay has to have power when the alarm is OFF. It is in the series chain of parts for the starter circuit. The starter circuit goes from Bat to ignition sw, to NSS switch, to alarm interlock, to starter solinoid. Any break in this series results in a No Crank condition.
I do not have the 129 schematic here at the moment , so I am unsure of which fuse feeds that circuit. See if your chart has that info. Might be referred to as ATA