Diagnosis
The relay on the main control board is clicking, but power is not reaching the heating element. This often points to a tripped or faulty high-limit thermal fuse.
How to Fix It
Unplug the heater. Let it sit for one hour to cool completely. Before plugging back in, ensure the room is above 41°F (5°C). Plug it into a different, known-good wall outlet on a different circuit. Try turning it on.
If That Didn't Work
The thermal fuse, a small white component usually attached to the heating element housing, may have failed open. You need a multimeter to test it for continuity. If it has no continuity, it must be replaced.
Heads Up
That click is a normal sound from the relay when powering on. Continuous rapid clicking indicates a failing control board.