How to solve Bluetooth connectivity issues in Android

When the app is not able to open your lock, it is needed to:

1. Turn off and on Bluetooth on your phone. This is possible pulling down the notifications bar and then pressing the Bluetooth icon, or going to the phone settings and disabling and enabling its toggle
2. Turn off and on Airplane mode on your phone. This is also possible from pulling down the notifications bar and then pressing the airplane icon, or going to the phone settings as well.
3. Restart your phone.