Mercedes Command Sat Nav System not location satalites

My E320 has the COMMAND system with GPS built in. Recently the GPS has not been picking up any signals from satalites and as such the GPS now does not work. I suspect a faulty aerial but I am not sure how to check this out. e.g. Is it the little thing on the roof (or is that just for the phone) or is it integrated into the rear screen . (I had the rear screen replaced about 6 months ago due to vandalism). If it is in the screen or the roof does anyone know the cable colours etc so that I can run a test on these. Any help appreciated.

You actually don't have a COMMAND, just a COMAND ;-)

You don't say it here but I assume you have a MY 2000 E320CDI, that is W210. The GPS antenna is not on the rear screen glass but as shown here:

Perhaps you could check that the GPS antenna was not injured when the car was vandalised.