If the alarm cannot be deactivated with the remote control key, e.g. if the key's battery is discharged - the car can be unlocked, disarmed and the engine started as follows:
Open the driver's door with the detachable key blade.
The alarm is triggered, the alarm indicator flashes rapidly and the siren sounds.
Insert the remote control key in the ignition switch.
The alarm is deactivated and the alarm indicator goes out.
Start the engine.