As with any DWA (German water and wastewater association) event: Simulate a breakdown!
Lower the window, properly lock the vehicle (using the remote control or with the key), then wait for a defined amount of time (at least 30 seconds, preferably a full minute), and then unlock the vehicle from the inside through the window (do not use the key from the outside, but unlock it from the inside).
Then open the door. If the DWA starts, then you have one, otherwise not

.