Any one of the clock hands are not functioning.
Parts of your clock were jarred loose if dropped from 3 or more feet.
Can't get the battery compartment open without breaking it.
Remove screw with small Phillips head screw driver.
Pry open with tweezers or plastic prying tool.
Device is not receiving power required to operate.
Make sure to replace the 2 AAA batteries.
The wires in your clock could be frayed or severed.
The battery door is too loose and keeping the batteries from creating a good connection.
There is no sound emitted from the device when the alarm should be sounding off.
Make sure upon opening the device that the wires are connected to the alarm module and are not severed or frayed.