It is the most horrible thing happened in my experience of Airbnb so many years. When I checked in with the guidance, I found it did not work. The pin provided by the host could open the smart lock at all. Then I tried to call the host and his cell phone number was not available. I couldn't find another apartment because it is too late to find a place with one week availability. Then I noticed in the Reviews that those things always happened before. OMG, why did the Airbnb still let the host lease the apartment? I didn't understand.