Audi A6 2000 engine won'e start!

Bought a 2000 Audi A6 two days ago, with 70,000 miles on it. The car
was running great till a few hours back when I parked it and got out
of the car. I saw a parking spot closer to my apartment so decided to
go back and park the car there. To my astonishment, the car completely
refused to start!! It was working fine 5 minutes ago, and now its not
starting at all. The engine is not even trying to start. There is a
yellow check light on the display with something which looks like a
engine with a slash across it. I have no clue what to do. I have 3
month dealer warranty, would the repair cost be covered by it or would
this be something major?

Are there any buttons/switches in the inside which I could have
pressed to stop the engine from starting??

Any help would be greatly appreciated!