HDMI Screen problem

Hi, I got an raspberry pi 400. But ist won‘t Connect to my hdmi Screen. it works with all scenes exept of mine😐. Du you have any idea why it’s not working? Thanks

Your screen is broken?! And "Won't connect" as a error description doesn't going to get you any help! Elaborate more.

There is no Output No Matter which device i use They are all working exept the raspberry pi