The LED of the button of the BPM+ can be:
- Blue if the BPM+ hasn't been paired with a mobile device yet.
- Green if the BPM+ has been paired with a mobile device.
- Orange if the previous measurement has failed. It then goes back to green.
https://support.withings.com/hc/en-us/sections/6215920350481-BPM
https://support.withings.com/hc/en-us/sections/115002570628-FAQ