I hope starting a new topic is ok, I couldn't find anything relevant when searching previous threads.

So our Polo developed a problem today.

When I try to start the car it doesn't do anything. Common sense would dictate dead battery, but radio and internal lights come on without a problem. What confused me is the clicking and random dash light flashing when you turn on the headlamps and try to start it. Once I also applied the brake and was greeted with a christmas lights display. My gf managed to make a video:

https://www.youtube.com/watch?v=GwbwxIrCtqI

Really stumped, any suggestions or ideas?