First make sure your QardioArm 2 is fully charged: Plug in the provided USB C cable and confirm that the green light on the side of the device is solid.
Download the free Qardio App from the App Store or Google Play Store, or visi www.qardio.com/download.
Open the Qardio App on your device and create a new user account, or log in with your existing credentials.
Enable Bluetooth on your device when prompted.
Pairing is always done through the Qardio App, and not via Bluetooth Settings.
On the dashboard of the Qardio App, swipe left until you see the plus icon "+" and tap on it. Select QardioArm 2 and follow the instructions to complete pairing and take your first reading.
In case of any difficulties with pairing, try switching off and on your Bluetooth. If your QardioArm 2 was paired before, try forgetting the pairing in Bluetooth settings and attempt to pair again via the Qardio App.