Your Corentium Pro has no off button. The monitor is designed to runs continuously. As it is a low-consumption machine it's able to run 1.5 years with a set of three AA alkaline batteries.
The button on the front is not an On/Off button. It's used to manually end the current measurement and start a new measurement.
When you start a new measurement with the front button, it will create a new "Unnamed#" dataset in the instrument’s internal memory. For client tests, it is best to use the App as you will name the data, set a duration and you may also set a delay. To start a ''Named'' measurement, go to ''SCHEDULE'' and enter the information.