Are you Apple Watch series 1 or series 2 user? You didn’t find installed keys on your Apple Watch?

Please try the following steps:

  1. Press and hold the side button until you see the Power Off slider.
  2. Drag the slider to turn off your device.
  3. After your watch turns off, press and hold the side button again until you see the Apple logo.
  4. Keep the Smart Key application open on your iPhone while the Apple Watch restarting.