ok, i tried to bring my device in demo mode, but no demo screen shows up, here my device sprecs und settings:
https://i.imgur.com/zvm8TgF.jpeg
https://i.imgur.com/JEfaUKm.jpeg
https://i.imgur.com/boAQsZO.jpeg
https://i.imgur.com/zjQ5H0b.jpeg
https://i.imgur.com/s1Hp0SG.jpeg
then i enter the described commen in the search bar
https://i.imgur.com/i5AQYic.png
tried it with restart via menu or via Power button, after restart my device shows no demo screen, it is the same screen like before