https://www.theregister.co.uk/2017/08/11/lockstate_bricks_smart_locks_with_dumb_firmware_upgrade/

Hardware biz Lockstate has managed to brick hundreds of internet-connected so-called smart locks on people's front doors with a bad firmware update.

The upshot is you can't use the builtin keypad on the devices to unlock the door. Lockstate's smart locks are popular among Airbnb hosts as it allows them to give guests an entry code to get into properties without having to share physical keys. Lockstate is even a partner with Airbnb.