Mercedes-Benz GL Operator's Manual page 86

SmartKey
84
Repeatedly tap the SmartKey against your
X
palm until battery = falls out.
Insert the new battery with the positive
X
terminal facing upwards. Use a lint-free
cloth to do so.
Make sure that the surface of the battery is
X
free of lint, grease and other contaminants.
Insert the front tabs of battery
X
compartment cover : into the housing
first and then press to close it.
Insert mechanical key ; into the
X
SmartKey.
Check the function of all SmartKey buttons
X
on the vehicle.