I had a similar problem with the SatNav in my VW Golf Mk7. Everything worked fine then - nothing. Everything else worked OK (radio, bluetooth etc.) bu the SatNav screen was completely blank. I tried the soft boot (hold the on/off button for 10 seconds - but that didn't work. Then I disconnected the battery - left it off for ~ 15 minutes, then reconnected and hey prestor - all OK. Some of the other functions lit up for a short while (auto brake, and other enginer-management lights) but they soon cleared. All OK now, and zero cost. Result.
