In the event the microphone becomes unresponsive, you can reboot it by holding the button down until the LED turns off and then back on as white. This may take a few seconds.
If you hold the button down longer and the LED turns blue, it will be in paring mode and may need to be paired once again with the iOS device.
Once the above two steps are complete, tap the mic icon in the upper right of the Audigo app and follow the prompts on the screen to set up.