To reset the Silent Beacon, hold both buttons down for 20 seconds. The LEDs will turn blue to let you know the reset has been completed. If you see the lights begin to blink blue, let go of the buttons; this is warning you that your Silent Beacon will enter Factory Reset Mode.
If you wish to Factory Reset your Silent Beacon (which will delete all phone numbers and additional firmware), hold both buttons for 30 seconds. You will know the reset is complete when the LED lights have cycled through all 3 colors.
You can click See how it works.