Since i figured out that the removable fan filter is not filtering anything
(because the case pulls air in right behind the filter)
i covered all openings, removed the magnetic door and because i lost the 3rd cover for the hdd slot, i designed and printed this copy of it......
Now the only way air can get in is through the filter up front like its supposed to :D
Fell free to Tipp me if i was able to help you
It takes some patience to fit the cover in, but it will work ;)