Unlocking the car to disarm it usually works. However, in certain situations, you need to disable it manually.
Note
Switching off a triggered alarm
If the alarm has been triggered, you can turn it off using the unlock button on your standard key or Care Key. If your key's buttons don't work, you have to disable the alarm manually.
Disabling the alarm manually
Place the key on top of the key symbol in the backup reader. It's located in the bottom of the cup holder.
Note
When using the backup reader, make sure that the area is free of other car keys, metal objects and electronics such as mobile phones, tablets, laptops or chargers. Such objects could disrupt the reader.
Turn the start knob clockwise and release it.
The alarm deactivates.