If the switch power supply is not lighting up while the exhaust fan works normally, use the following steps to troubleshoot:

1. Check the input voltage of the low-voltage power supply (refer to the video).

          If the voltage is normal, remove all the loads on the power supply

1. With all loads removed, if the indicator on the power supply comes on, then one of the loads must have a short circuit.
2. Plug back all the loads to confirm which one of them is faulty.
3. If the power supply still won’t light up after the step-by-step check in step 2, then replace the low-voltage power supply.
4. If the input voltage of the power supply is 0, there must be a wiring problem with the wiring between the button switch and the power supply, check the wiring and replace any parts as needed.