So i had the Problem that my GMod Servers would always fail their Update through SteamCMD with the Error Code 0x606 or 0x602 .
The Error Codes are just saying that SteamCMD cant copy the new downloaded Files to their destination or that you don't have enough space to download the Updates in the first Place.
Anyway the Problem in my case was that OpenGamePanel set's the immutable Flag on the srcds_run binary.
So just run
sudo chattr -i srcds_run to remove the Flag.
OpenGamePanel will set it again the next time you start the Server.
Hope i could help some people with the same Problem, leave a comment if i did :)