- There is not any power going to the unit.
- The unit is not armed.
- The subassembly is damaged or gone bad
- Verify there is power to the unit (fresh 9 volt batteries). Try resetting after installing new batteries.
- Verify the Key cylinder is engaging the microswitch. Verify the microswitch at the key cylinder is good.
- The subassembly is bad and will need to be replaced.