DeWalt 20V Grinder acting weird - battery won't charge fully, makes grinding noise

Hey folks, having a weird issue with my DeWalt DWE402 grinder. The battery (20V XR) won't charge past 2 bars, and when I try to use it, it stalls under light pressure and makes this weird grinding/rattling noise from the motor area. It's only about 18 months old. Already tried cleaning the contacts and a different battery - same issue. Any ideas before I take it in?

Classic brush issue, OP. Those DeWalt grinders eat through brushes faster than most tools. The grinding noise + stalling is almost always worn brushes or a stuck brush spring. The battery thing might be unrelated - have you tried that battery on another tool? Could be the charger too. I've had three of these apart - pop the housing and check the brushes first. If they're under 1/4", replace 'em. Cheap fix.

Dan's probably right about brushes, but that battery symptom is suspicious. OP, does the charger light blink or stay solid when charging? If it's blinking, it's detecting a fault. Could be a bad cell in the battery pack or the tool's BMS (battery management system) interfering. For the noise: remove the disc and guard, spin it by hand - feel any gritty resistance? Might be bearing wear if it was used heavily. Restoration tip: I've salvaged worse by replacing bearings and brushes for under $30.

Agree with both. Seen this exact combo on a grinder I restored last month. Turned out to be two problems: 1) worn brushes causing noise/stalling, and 2) a dirty thermal sensor in the tool making the battery charge weird. Clean the sensor near the battery slot with contact cleaner. For the brushes, DeWalt part # N483428 if it's the brush holder type. Easy 20-min fix if you're handy. Let us know what you find!

Thanks everyone! Checked the charger - solid red light, not blinking. Took the housing off like Dan suggested, and yep, brushes are totally worn down to nubs. Ordered the part Pete mentioned. Gonna clean the sensor too. Appreciate the help - saved me a $100 service call!