XBOX ONE X controller connection problem

Hello everyone,
today i tried to clean my XBOX ONE X like in this video (https ://www.youtube.com/watch?v=XLxX40Zq39Y&t=261s).

I took it apart like in the video, removed the dust from all the parts (with canned air) and put it back together.

Afterwards I tried, if the console is still working, but I had to discover, that the console wouldn`t start by pushing the power button on the controller. It would only start by using the button on console itself.
After starting my Xbox i tried to sync my controller, but after pushing the sync-button, the light on the front cover, didn’t start to flash.

At first i thought, that maybe I messed up putting the ribbon cable or the connector which come from the bottom part back together. So i took it apart, checked the connections and tried again with the same result.

I tried using my Controller with an USB-cable, which works fine. I also checked if everything else seems to work and it does. Then i tried to connect my controller like this guy (https ://www.youtube.com/watch?v=RixeGspT8Uw) but it failed.

I guess some cable or connection is broken, but I’m not sure. Would appreciate if someone could help me.

Greetings from Austria

Philip