Caesar, something things just break. I have one of those old fashion lights where you pull the chain to turn it on and off. One day, I pulled the chain and the light broke, locked up. It just broke.
Not every damage is the result of the guest. You would have a hard time collecting on a leaky fawcett because once and a while, fawcetts need new washers. Once and a while ceiling lights break.
It helps your case if you can show how the light was broken. It helps if you investigage so you can show Airbnb that the guest is responsible.