Below is the link to your manual. I would say recheck your batter seating. Follow directions for turning off power before replacing the battery.
OPERATION, TESTING & MAINTENANCE
OPERATION: The heat alarm is operating once the power is connected and turned
on (the battery must also be installed). When air temperature above 135oF is sensed,
the unit sounds a loud alarm which continues until the air is cleared.
This alarm incorporates the internationally recognized horn signal for evacuation. During
alarm mode, the horn produces three short beeps followed by a two second pause
and then repeats. This pattern is somewhat different than the previous alarm sound,
which continually beeped.
STANDBY CONDITION: The red LED flashes once every 40-60 seconds to indicate
the unit is properly functioning.
LOCAL ALARM CONDITION: The red LED flashes rapidly and the unit emits a loud,
pulsating alarm sound.
REMOTE ALARM CONDITION: The red LED is off and the unit emits a loud, pulsating
GREEN LED: The green LED is on whenever AC power is turned on.
TESTING: Test by pushing the test button on the heat alarm cover until the alarm
sounds, then release. The alarm sounds if all electronic circuitry, horn and battery are
working. If no alarm sounds, the unit may have a defective battery or other failure.
If this helps out please press the accept button. This is how I get compensated for my TIME. Feedback is appreciated and bonuses are accepted with a smile. Brad