When you are standing beside a bike, you can unlock it by tapping the "scan QR code button" at the bottom of the app home screen
A camera mode will open, and you should point your phone to the QR code on the handlebars or on the rear of the bike. When you scan the code, you will hear the unlocking sound after a few seconds.
In case of the lock does not open, please close your App, and wait for 15 seconds. Reopen the app and try the whole process again, or alternatively try another bike.
P.S. Before you start please make sure that the bike is in good condition. You'll have 1 minute free to return the rental in case there is an issue with the bike