What is the first step to take if the controller display is blank?

When the controller display is blank, the first step to take is to check the power supply and fuses. This is because a blank display often indicates that the device is not receiving any power. By verifying that the power supply is functioning correctly, you can determine if the issue is simply related to a power interruption or a blown fuse. Ensuring that the controller is properly powered is essential before proceeding to further diagnostics, as no display may lead to incorrect assumptions about the controller's operational status.

Inspecting valves for clogs, resetting the controller, or replacing the battery are important troubleshooting steps, but they should come after confirming that the controller has power. If the power source is intact and the display is still blank, then other issues can be investigated.