Won't power-up or start - please help

Just bought a 2002 S4 new in July. 600 mile check went fine. Now it's got 3000 miles without problems until...

Went to start it up last night, and the bike wouldn't power-on. No dash light up, no horn, no starter, nothing. When I turn to the park position, however, the headlight does shine.

Tried to push-start it down a hill a few times without luck, but somehow (maybe just the act of rolling it around) I get the dash to come on for a second as I'm parking it and start it up. I drive it around town for 20 minutes, hoping the battery just needs a recharge. I park it, turn it off, and then try to turn it on again. Same problem, no power.

Fuses are all OK. I also tried the red "master" key without luck.

The bike is still under warranty, but the next available appointment at the dealership is OCTOBER 2! So I'd rather take care of it myself ASAP.

Any suggestions as to the possible problem?

Thanks a lot,
Benjamin Burack