Well, it's the right place to post when it comes to the Challenger.
It would help us to help you if you outlined the steps you did to achieve this. Sometimes, a step or 2 can be missed, even when following an instructional video.
There's a shutdown checklist. But as a last resort, have you tried creating a new airframe?
Why? You can leave it installed, and then come back to it. There's no reason to uninstall.
This is a hobby, Stefan. Try to treat it as such. Set aside a block of time where you can try to enjoy it. If help is needed, we're a few keystrokes away.
There are many videos that go over many different areas of this add on. Particularly from Reflected Reality Simulations. Very highly recommended.
The product page is very clear with regards to the complexity of this add on. It's not a difficult add on to get into, but it is complex and extremely detailed.
If it's going to get you this frustrated or annoyed, I suggest you take a small break and come back. There are many people willing to help you overcome any obstacles.