I received my replacement box! Connected it to TV, but i did not connect LAN cable. It has firmware v1122.3 on it and blacks are black again (as far as i can see in daylight)! So the firmware is stored in the box, not on TV.
Now need to figure out if i want to update to 1123.1 (latest good firmware in Europe) over USB and then make sure the auto update is disabled. Then i should be good...
EDIT: This damn thing turns auto update on when you set up Smart Hub! I set up Smart Hub and checked the setting immediately after that and auto update was on! I set it to off again and removed LAN cable as fast as i could (it was already displaying that there is a update to 1130 on the right side). I hold my breath and turned TV off and On again... I'm still on 1122, so it seems it could not finish downloading the update before i pulled the LAN cable. Samsung will hear from me when this crap updates itself without my permission.
EDIT2: It seems i'm good now. I have Netflix and good picture, everything works as it should. I'm still on 1122. Like i already wrote, i turned auto update off again after setting up Smart Hub and it seems it stays off now (i have done a few restarts).
It seems i need two One Connect Boxes, one for watching TV and another one for testing Samsung firmware updates. Samsung should really consider shipping 2in1 box
EDIT3: This damn thing updated to 1130.9!!! I had auto update off and it is still off, but it updated anyway. Picture is again ****ed up, damn Samsung.
EDIT4: Lost Netflix too. I can't believe this.