Our team suggests picking your REST session and then connecting your REST. When you tap on a session it will then ask you to "Connect to REST" before you are able to customize your session. You are only able to connect when the green light is on. The green light stays on for 30 seconds if it is not connected to the app. After connecting with the app the green indicator light will stay on until you select a session.
You can also plug in your REST to the charger before opening the Umay app and it will automatically connect to the app.
Please let us know if you encounter further difficulties.