DIAGNOSIS The tool isn't getting power. The most common cause is the battery not making a solid connection in the tool's port, often from sawdust buildup.
FIX Clean the battery contacts. Power off, remove the battery, and blow compressed air into the tool's battery port and across the battery's metal contacts. Use a clean, dry cloth or a pencil eraser to gently scrub any visible corrosion or carbon scoring off the contacts. Re-seat the battery firmly until it clicks.
IF THAT DIDN'T WORK Test with a different, known-good 20V MAX battery. If it works, your original battery's protection circuit may have tripped. Let it sit for 30 minutes off the charger, then try it again.
HEADS UP Don't use contact cleaner or liquids directly on the contacts, as residue can insulate the connection. This tool doesn't have a brushless motor, so a failed trigger or switch is a less likely but possible culprit if cleaning doesn't help.