DIAGNOSIS The 'Popcorn' sensor button is calibrated for a specific weight and bag type (typically 3.0-3.5 oz conventional bag). Using smaller bags, different brands, or 'light' popcorn will often result in overcooking.
FIX Do not use the Popcorn button. Use manual time. For a standard 3.0-3.5 oz bag, start with 2 minutes 30 seconds on High power. Listen closely. Stop the microwave when pops are 2 seconds apart. This almost always prevents burning.
IF THAT DIDN'T WORK If even manual times burn, your microwave's power output may be higher than labeled. Reduce time by 15-second increments. For smaller snack bags, never exceed 1 minute 45 seconds initially.
HEADS UP The sensor measures steam, not sound. Bag design and butter content affect steam release, making the sensor function unreliable. Manual timing is the only precise method.