I've just had my new radio working on my audi tt 2003, Intill I disconnected it to connect to aerial. I've blown the 20amp fuse, swapped it with a new one but it's still not working The fuse in the back of the radio is fine. Anybody know what it could be? Is there any other fuses I should check?

SOURCE: Audi TT fuse box

It is in the end of the dash board. open the drivers door so you can see the end of the dash and ease the semi circle shaped cover off. There is a fuse pulling tool in there too ;o

SOURCE: audi tt 180 quattro car wont start. EPC and E-M system lights on

I would suggest you check oil levels etc. Generally these cars suffer from the air mass meter / air sensor problems aswell as coil problems too. Did you ever get a solution to the problem?

SOURCE: 2003 Toyota Echo radio/clock not working.

Disconnect your negative battery cable for about 10min. After you re-connect, the stereo should reset itself and start functioning. Best of luck!
Greg

SOURCE: 2005 Audi TT Master Fuse location

Had a similar problem audi come into my shop.  No headlights, blower motor would not work, wipers would not work.  After dinking around found ignition switch wires had burn't up.  Remove top steering column by taking out two very small philips screws from under column.  Look at top LH side of column w/ top cover removed.  Probably will find wires burnt up.  

SOURCE: Hyundai Elantra 2003 electrical problem

I found that while checking my fuses that i had pulled out what looked like a black plastic "fuse puller" that was actually some kind of jumper. I had accidentally re-installed it reversed. I reversed it back to its original position and all lights, clock, radio, etc.. work normal now.