This menu shows the current battery voltage, (in German, will be indicated by IB:14.1) allow you to activate Dynometer Test Mode (this completely disables all ESP functions to test the engine output on a roller dynometer and it is not designed for highway use. Unless you have a dynometer and are tuning your car, never alter this setting), reset the service indicator, configure the Dealer Number that conducts the service, displays the VIN number, and the software versions installed on the Instrument Cluster.
Incidentally, it actually has nothing to do with the COMAND or any of the COMAND settings. This is designed for workshop use when the vehicle is in for service to acknowledge a service has been performed if the workshop does not have Xentry - otherwise it is typically done in Xentry.
To access this menu - do the following:
Get in the vehicle and close all of the doors. Turn the ignition to the "1" position and the only thing on the Instrument Cluster that comes on should be the illustration of the red bald man with the pillow impacting his face which extinguishes after a short while. Ensure the cluster is displaying the Trip Odometer and Main Odometer, and nothing else. If the Audio, Telephone, etc. menus, or the digital speedometer is displayed, it will not allow entry.
After the above conditions are met, press Phone Answer on the steering wheel control, and on the other side, OK and hold them for several seconds. The battery voltage should be displayed after a few seconds.