Makita grinder battery not charging — anyone else?

Hey guys, my Makita 18V grinder battery won't charge. It's the 5Ah one, about 2 years old. Plug it in, charger blinks red and green then solid green like it's done but it's dead. Tried other batteries they charge fine. Any ideas before I buy a new one?

Classic BMS issue. If it's still under warranty, try Makita support. Otherwise, you can try jump-starting it with a good battery by touching terminals for a sec — YouTube it. But be careful, could be a bad cell. I'd just get a new one, not worth the fire risk.

I'm a DeWalt fan myself, but Makita usually lasts. Have you cleaned the contacts? Sometimes grinder dust makes crap connection. Also, try leaving it on the charger for 24 hrs — some chargers need to "reset" the BMS.

I've had this exact issue with a 4Ah. It's likely a cell dropped below 2.5V and BMS locked it. You can try to manually charge each cell with a lab power supply, but unless you have one, it's toast. Honestly, after 2 years of heavy use, batteries are consumables. Get a new one.

Thanks all. Tried cleaning contacts, no luck. I'll try the jump start trick Chris576 — worst case I'll buy a new one. Appreciate the help!