Mercedes-Benz 2008 S550 Operator's Manual page 486

Turn the mechanical key clockwise to
position 2 to lock the trunk.
The trunk remains locked even when the
vehicle is centrally unlocked.
i
You can only cancel the separate trunk lock-
ing mode by means of the mechanical key.
Insert the mechanical key in the trunk
lid lock.
Turn the mechanical key counterclock-
wise to neutral position 1 to unlock the
trunk.
You can now open the trunk
( page 479).
Controls in detail
Trunk
485