Colour not correct

All of a sudden the colours changed. I can’t get it back to normal (I did everything the manual suggested). What can I do?

Is it the source blaiming for the colors?
Eg ATV4 does support Color settings refresh.
I have done that after switching numerous back-and-forth testing SDR and HDR settings with various
Chroma and RGB (high-low).
You can also go back to factory settings on U4 which helps greatly to re-adjust or re-install firmware (which is in my opinion more or less the same if you are on the latest version and do a factory reset.
Menu 4,3 or so meaning left menu bottom (4) and eg 3rd row. Good luck!

If that is not the case, then it is probably the led engine who has a defect (overheated leds so degradation in colour or absence of a colour. Try to connect a laptop to the projector and run a display test program for the primary colours, also black and white. If white is not perfectly white then some of the leds are gonna die soon…good luck