To unlock you mean RESET.
Best way is to use MBCan tool
http://www.autodijagnostika.biz/prog...an-reset-tool/
If he need to personalize (activate to car)
He need:
DIAGSPEED 5500€
CARTOOLS 3000€
SIMONTOUCH (!?)
AVDI BGA 2500€
MERCEDES INSTRUMENT 6000€
NECPRO57 5000€
We use diagspeed and cartools (CAR set is best, engineering tool)