Using a nickel, since other coins tend to destroy the plastic, remove the battery port door. Then, remove the battery. While the battery is out, depress the top and bottom switches for ten seconds and then release them. Wipe the battery clean so that it is void of fingerprints and any other debris. Re-install the battery with the negative side down. Make sure the O-ring is correctly positioned in the case groove. Re-align and install the battery port door, making certain you completely seal it. Now, turn the unit on. If the accumulated distance does not read zero, repeat the hard reset. Once the accumulated distance is zeroed, you can enter a recorded calibration number if you have one. If you were experiencing difficulty with your stroke rate readings, put the unit in the 0-Stroke mode.