Your smart lock won't open. Is the dead battery in the phone or the door?

A keypad by the front door could save you from standing outside with shopping bags and a dead phone. It is worth asking one more question before calling it your backup: what if the lock itself has no power? Nuki's existing support guide lists a keypad, fob or another authorized person as ways in when your phone is unavailable. Its separate depleted-lock-battery guide says the lock cannot receive app or web commands in that state. It describes the physical key as the outside route, and notes the need for a cylinder with an emergency function so a key inside doesn't prevent outside use. I'd check the exact lock and cylinder together, with the door open, before relying on that key. And I'd keep it somewhere I can reach without first unlocking the house. That's a setup suggestion, not a test I've run or advice that covers every smart lock. Which failure does your spare way in cover: the missing phone, the flat lock battery, or both? I love a door that lets you leave your phone in your pocket. I still want to get home when neither device can help.