Diagnosis
This is typically a failing tactile membrane switch behind the control panel button. Dust accumulation or wear from repeated presses can cause intermittent contact.
How to Fix It
First, ensure the issue is not a loose power connection. Unplug the unit from the wall outlet and plug it directly into a different outlet, bypassing any power strips. Press the power button firmly and deliberately in the center. Listen for a faint click.
If That Didn't Work
The control panel assembly is likely defective. The AC5350B's buttons are part of a sealed panel. Replacement requires disassembly and a new control board. Contact Guardian Technologies support with your model and serial number for warranty evaluation or part purchase.
Heads Up
Avoid using excessive force. Mashing the button can damage the internal switch further or crack the plastic fascia. If the unit is under 3 years old, it may be covered by the manufacturer's warranty.