Compaq 341251-002 Operation And Reference Manual page 49

IMPORTANT:
I
Even though an audio alarm may be silenced, the condition that caused the alarm
may still exist. For information on procedures to follow if the UPS detects an alarm
condition, see Chapter 6, "Troubleshooting."
I
If a utility power failure caused the alarm (AC Input LED 1 or LED 4 red), the alarm
will be silenced after utility power is restored.
Operation 3-13