See also:

Removing the mechanical key
Removing the mechanical key Push release catch 1 in the direction of the arrow and at the same time, remove mechanical key 2 from the SmartKey. ...

Important safety notes
WARNING When leaving the vehicle, always remove the SmartKey from the ignition lock. Always take the SmartKey with you and lock the vehicle. Do not leave children unsupervised in the vehicle ...

Vehicle remote opening
If you have unintentionally locked your vehicle (e.g. the SmartKey is still in the vehicle) and a replacement SmartKey is not available, the vehicle can be opened by a Mercedes-Benz Customer A ...