At high Intensity some frequencies will create an audible hum and at full intensity there can be the occasional buzz. If you can hear this with headphones on then please contact us and provide details so we can assess if there is an issue.
If there is slack in the lanyard then the metal clips can rattle against each other, or the device will rattle if on top of a clothing button or similar, so check that as well.
If the Sensate light is flashing green and yellow, it is in update mode and will not switch off until the update is complete. If Sensate runs out of charge, you will need to fully charge it, before continuing the update. You will not be able to use Sensate until the update is complete.