I have a 2003 A4. My radio won't turn on and the display says SAFE. Any ideas what happened and how I can fix it?

Did you or someone disconnect the battery? The radio has a lock which prevents theft. When you purchased the car, it should have come with a 4 number code and instructions. there are included in the instruction manual for the radio. Instructions for resetting are also in the manual for the radio.

I had the same problem - thanks to this forum I found out that on my '98 the four digit code was printed on a sticker affixed to the passenger side of theinside of the spare tire well. There are a bunch of numbers - just look for a four digit number all by itself. Just follow the directions for code entry that are in your owner's manual. Hope this helps.

Welcome to the forum a4kelly!

If you don't have the code, you will have to go to your nearest Audi dealer to have them look it up for you on their computer.
Other than that, what the guys above have said is accurate.

Also... Welcome to the forum ChrisB!