https://zigbee.blakadder.com/index.html
To pair the device, reset the device by pressing the pair button exactly 4 times quickly. Then trigger the configuration of the zigbee-device by holding the pair button for 10 seconds.
pair by turning it off and on 6 times in quick succession
https://www.youtube.com/watch?v=mJm9YpPrGzk
push the vallhorn device link button 4 times in max 5 sec