Hey Bob, found out today you and I have the same problem...today, without warning and to my surprise,my F90BT screen was dim when I started it today, went into settings adjusted the screen brightness, drove over for about 5 minutes stop into the store, came back out about 30-45 minutes and noticed the problem that I've tried to fix since returning. Tried everything you did to no avail.
Does anyong have a solution?
V/R
Randy