How can I reset the anti-theft system in my Audi A2?

I recently installed a new battery in my Audi A2 and now the anti-theft system won't let me start the car. What can I do to reset it?

To reset the anti-theft system on your Audi A2, try putting the key in the ignition and turning it to the 'on' position for 10 seconds. Then turn it off and remove the key before trying to start the car again.

You can also try disconnecting the negative battery terminal for a few minutes and then reconnecting it. This may reset the system and allow you to start your car.