Softener will not start regeneration at all; pressing manual regen button has no effect

Safety first: Verify the unit is plugged in and the outlet is safe before proceeding.

Step-by-step checks:

• 1. Confirm power: Check that the display is lit and stable. If blank or flickering, troubleshoot the power supply first.
• 2. Check keypad lock: Some Marlo models have a keypad lock feature. Refer to the manual to unlock the keypad and then try the manual regen button again.
• 3. Test other buttons: If only the regen button is unresponsive while others work, the keypad membrane may be partially failed.
• 4. Attempt regen from installer menu: If available, start a regeneration from the advanced menu. If this works, the front-panel button circuit is suspect.

When to replace parts: Replace the Marlo keypad/display assembly if specific buttons fail. If no manual regen command is recognized from any interface, replace the Marlo control board.