My son left the sunroof open and the electronics on my 2008 A6 got wet....really wet. Radio, GPS etc come on for a second but then go dark.Anyoe can help before I take it to dealer. Ive let it dry out for about three days now.

 

As long as they dint get powered up, they're usually fine once they dry. Yours got powered up which is when most damage occurs. Since they come on for a second before shutting down, they're probably tripping an overcurrent protection - that would imply water still inside shorting the power out. Letting them sit isn't enough. Remove them, open the cases up, and dry them thoroughly with a hair dryer and alcohol and then try them out - it may fix the issue.