Holidays and Traditions How long will a house alarm go off? What do you do when a house alarm won't stop? - Remove the cover. - Remove the battery. - Press and hold the tamper button. - Insert the battery while holding the tamper button. The LED light will flash. Hold the button until it stops flashing. - Replace the cover. How long should an alarm sound for? about 5 to 10 minutes Related Posts:How to install a FireAngel ST-620 smoke alarm - Replacing YouTubeFIREANGEL ez-212 user manualEverStart Maxx Lead Acid Marine & RV Battery, Group Size 24DC, has been reviewed.Amazon.com has a group 27 battery weight for deep cycle and electric trolling motor batteries.How long will the internal battery last in a nest thermostat?