This is on another audi forum but posted about an A4, may be a similar way of doing it on your a3. Thought I would post incase it helps......
1. Removed front grille. Chrome trim piece stays attached to grille. Don't take it off. Start at the top corners. Use a flat screwdriver to pry with. Place a rag between the paint (hood) and the screwdriver. Once you get the top loose pull it towards you, it will come out.
2. Unbolt hood latch from hood. You will see 3 10mm nuts that attach the latch to the hood. 2 up front that are easy to get and 1 in the back that is a pain in the a__. Use a short 10mm open end wrench and a lot of patients. Once you have the off. The hood will open up.
3. Get the catch out of the latch. On the back of the latch you will see where the cable pulls on the latch. Pull it and the latch will release. Thats it.
I have heard of other methods. ie removing the belly pan and reaching up behind the radiator to pop the latch. I don't see how this is possible on the 3.0. Might be on the 1.8t. The grille just snaps in with clips. If you are careful you wont break any.
