Hello KDE (Neon) community

I moved and simultaneously started to work in a different county for some week, that's why I wasn't using my computer for round about 4 months.
Now since I am back home, I sat up my pc and started it, but after unlocking the FDE (FullDiskEncryption) I get nothing more than a black screen.
I tried some things, like removing every hard drive except the main drive, removed everything that isn't necessary and so on, but had no luck.

Now I found a way to use my pc again:
After entering my FDE password, I hold down shift and select the recovery option. In the recovery menu then, I just chose the "resume" option (continue normal boot) and then I get to see the login screen (SDDM) and can use my pc normal, except that KDE Neon is now in the "nomodeset" state.
I updated everything and rebooted, hoping that it fixed my problem, but again, no luck.
I then checked every tab in KSystemlog for errors, but there is not a single error...

The problem has do be to do with the fact that I didn't used my pc for so long, because before I went to England and moved, everything worked just fine.
I turn to you guys, to hopefully get some advice what to do, except for just reinstalling everything.

Kind regards, Juri.

I have some more infos on that topic:
I created a live usb stick with the latest user edition and faced the same issue: black screen after grub.
And it shows the same behavior as my main SSD, booting in "graphics safe mode" works.

Since my graphics card is only a few months old, I would be surprised if it's a hardware fault, combined with the fact that the graphics card works in safe mode. But on the other hand, it doesn't even work with a clean live system.

So I guess when no one has an idea how to dig deeper, I have to buy a new graphics card and hope that my current one is the culprit.