No two smoke detector or smoke alarm models
operate the same way. One cannot look at a smoke detector or smoke alarm and make any assumptions about what the indicator lights may mean. The only way to tell with certainty what the indicator lights may mean on a smoke alarm or smoke detector is to read the instruction book that came with the devices. Even within the same manufacturer, different models of smoke detectors and smoke alarms will operate differently. Therefore, it is necessary to have the instruction book for your smoke alarm or smoke detector and also to keep it for future reference.
If smoke alarm or smoke detector chirping (smoke alarm beeping) is your difficulty, it may be helpful to recognize that it can be surprisingly difficult to pinpoint which smoke alarm or which smoke detector is chirping. To determine with certainty which smoke alarm, smoke detector is chirping requires placing your ear quite near the suspected device and waiting until you hear it chirp again. To isolate which smoke detector, smoke alarm may be chirping one should close intervening doors to various rooms equipped with either a smoke alarm or smoke detector to make it easier to discern from the ground.