Please install the batteries. Use a tool to open the case and make sure to close the case properly after having inserted the batteries.
Hit the button in the Ozom App to set the Ozom Box into search mode.
Keep the large button on the front side of the device pressed for 10 seconds. A beep will indicate that the adding process has started.
It may take some time (up to a few minutes) before the OZOM App connects to the CO Sensor and displays a progress bar.
If adding is not succesful, wait until the blue button turned blue again. Then try again, starting from Step 2.