1, make sure there is no big metal object around.
2, power on the detector.
3, then power off and keep pressing the power button for around 5 seconds. Do not release the power button until the light comes on again then take your finger off the button.
4, After approx 2 seconds there will be 2 beeps, this means the recalibration was completed successfully. However, if you hear If 5 beeps then recalibration failed.
There is a video walkthrough of this process here https://www.youtube.com/watch?v=jjjlK-iEsjg
If this does not work please contact your local Quest dealer or distributor. If you have no local dealer/distributor you can contact Quest directly on firstname.lastname@example.org