I was running U21 Ver. 6.1 and upgraded to the latest, U29 Ver 14.1. I couldn't access the service screen from either version. Is it the case, that I'd need to find an earlier version to get access to that screen to shut of the nav nag? Or will that not work with updated versions and I'll need a hardware hack? Followed the standard instructions about going to settings | volume and touching in the Left top and bottom in sequence twice. Nada. Looked high and low to see if there was another way to get to this screen. I can get to the diagnostic screen. Anyone have success at doing this with up to date nav?