Give a try in settings to display canbus information on screen.
=> Dudu-Lai's post
With this method i checked that canbus information was received normally by the unit. Every click on physical button or screen button was returned in the canbus "message" on screen.
So my only problem was to find the right canbus box setting.
If no information was displayed, perhaps your physical canbus connection between unit and frame have a problem.
Here is my video when i tested this method https://youtu.be/wlaCiuvqnm4