Has anyone ever heard of a mini Cooper convertible top opening by itself? No key in ignition. No one in car. Doors locked. It was raining at the time. My car (2009) was flooded. Now the airbag light is on.

 

If you bumped the key and it held the unlock button it will automatically open the top, This is normal function for people that want to put the top down while outside the car, my older R52 convertible did this also. You have to make sure you dont have your keys bumped and holding that open button in your pocket and be close to the MINI.

You can turn it into your insurance company as a claim. I have seen some people do this when they have a flood.