BBU Audible Alarms
If there is a problem with your BBU (Battery Backup Unit) , an alarm will sound for 2 seconds and be silent for 58 seconds. This will be repeated until you press the Alarm Silence button. Once you do, be sure to check the lights on the BBU to find the issue (see above). Below are the most common reasons for the alarm to sound:
Low Battery alarm is silenced after electrical power returns, the battery is fully discharged or removed from the BBU
Replace Battery alarm is silenced when the battery is removed
It's possible that after electrical power is restored, you may still be without FiOS service. Sometimes resetting your Battery Backup Unit (BBU) is needed.
To reset your Battery Backup Unit:
Unplug the electrical power cord of your BBU from the wall outlet.
Wait one minute and then plug the cord back into the wall and see if the Optical Network Terminal (ONT) resets itself.
If the ONT resets itself then your FiOS service should come back online. If it doesn't you can try to reconnect the battery, if one is maintained in the BBU.
To reconnect the battery in your BBU:
Unplug the electrical power cord of your BBU from the wall outlet.
Open the battery cabinet on the BBU (you may need a screwdriver to do this).
Disconnect the battery leads and wait 2 minutes. Reconnect the battery leads.
Put the battery cabinet back on and then plug the power cord back into the wall and see if the ONT resets itself.