How can I troubleshoot the battery drain in my Audi A2?

My Audi A2's battery keeps draining, even after I've replaced it with a new one. The car is only a few years old and I haven't been using any power-consuming accessories. How can I troubleshoot and fix this issue?

First, check for any electrical issues by inspecting the battery terminals and connections for corrosion or loose wires. If everything seems fine, the issue may be with the alternator.

Try using a multimeter to test the voltage of the battery while the car is running. If it reads below 13.8 volts, the alternator may be malfunctioning and not charging the battery properly.

Another possible culprit could be a fault in the car's electrical system. It may be worth getting the car scanned for error codes to identify any potential issues.