Re: no warm temp greyscale adjustment
Don, I seriously do not think there is anything wrong with your display.
There is nothing that a manufacturer will do for you relating to warranty if the display is showing an “adequate” image.
Generally speaking, I suggest that none of my clients ever mention accessing the service mode on a display. While doing this does not invalidate the warranty it does give the manufacturer a stool to say “you did it to yourself, so the warranty is now invalid”.