Just saw this post. The scrambled screen issue is due to a dirty ribbon cable connection. That is all it is. I first had the issue where I would loose the color blue. The ribbon cable from the screen to the nav unit has no connector on it, just bare conductors on the end. The ribbon cable plugs into a receiver/connector in the Nav unit that clamps down on it. I pulled this cable out and cleaned the contacts. That solved the problem for a couple of years and then one day I had a scrambled screen. I was able to just tug lightly on the cable behind the screen and fix the issue, but I need to take the unit out and clean the contacts again. Use Deoxit contact cleaner. You can buy it at Radio Shack. It is also popular amongst us audiophiles for cleaning our audio cable contacts. Very good stuff. So the problem is not your screen, just a corroded connection.
2007 3.0si w/Sport Pkg, Navi, Leather, Strut brace, garage door opener and delete airbag warnings on sun visors