May be an answer here
http://forums.mercedesclub.org.uk/archive/index.php/t-11207.html
Maurice
April 2009
thanks Maurice,my key type is a flip out metal, 3 button remote ,my car is a merc200E YEAR 2000.I NOW HAVE NEW BATTERIES IN MY KEYFOB MY PROBLEM NOW IS HOW DO I RE-SYNC ANYONE PLZ??
DANNY
April 2009
depends upon the key type / age of car.
Early cars with oblong key holders and flick out keys comne apart in the middle along the seam. seperate using coin.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.