With the power off andthe scale on a stable surface, hold "g" and press "on". Some number will show up, probably a negative number. Press the "on" button again and the scale should display "Zero". Wait until it says "200.0". Gently place a 200 gram weight on the scale and wait a few seconds. If your successful it will say "Pass" and your scale will work again, yay! I found this out by trial and error. Good luck.