If the vehicle can no longer be unlocked with the SmartKey, use the mechanical key.
If you use the mechanical key to unlock and open the driver's door, the anti-theft alarm system will be triggered .
■ Take the mechanical key out of the SmartKey .
■ Insert the mechanical key into the lock of the driver's door as far as it will go.

1 To unlock X Turn the mechanical key counter-clockwise to position 1.
The door is unlocked.
■ Turn the mechanical key back and remove it.
■ Insert the mechanical key into the SmartKey.
Qualified specialist workshop
An authorized Mercedes-Benz Center is a
qualified specialist workshop. It has the
necessary specialist knowledge, tools and
qualifications to correctly carry out the work
required on your vehicle. ...
Traction
WARNING
The traction grade assigned to this tire is
based on straight-ahead braking traction
tests, and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics.
...
Problems with your vehicle
If you should experience a problem with your
vehicle, particularly one that you believe may
affect its safe operation, we urge you to
contact an authorized Mercedes-Benz Center
immediately to have ...