How do I reset the electronic filter check indicator after replacing a filter?

With the unit powered on, press and hold the illuminated 'Check Filter' or 'Check Pre-Filter' button for approximately 2 seconds until the light turns off. If you replace a filter before the indicator light comes on, plug the unit in but do NOT power it on, then press and hold each button individually for at least 5 seconds to illuminate the light, then press and hold each button again until the light turns off to reset it to its original clean status. (Page 3)