Battery not charging on my orbital sander - any ideas?

Hey all, my 18V cordless orbital sander stopped charging. The charger light blinks red and won't turn green. Battery is only a few months old. Tried a different outlet, same thing. Any thoughts before I toss it?

First, check the contacts on both battery and charger for dirt or corrosion. Use a dry cloth. Also, might be a thermal cutoff – if the battery got too hot, let it cool for an hour. If still no go, could be a bad cell. Try a multimeter on the battery terminals.

Happened to my drill last year. Turned out it was the charger, not the battery. Got a new charger and it worked. If you have a buddy with same battery, try their charger.

Good ideas. Checked contacts - clean. Let it cool overnight, still blinking red. I don't have another charger. I think the battery is toast. Any way to fix a dead cell?

If it's under warranty, contact manufacturer. Attempting cell repair without proper gear is risky and can cause fire. Better to buy a new battery. SawDust, check your charger too with a multimeter - should output ~20V.