Help! My impact wrench making weird grinding noise and battery won't charge

Hey guys, first post here. I'm an apprentice plumber and just got my first impact wrench (a used Craftsman 20V). It was working fine for a couple weeks, but now when I try to use it, it makes this awful grinding noise and sometimes just stalls. Also, the battery won't charge anymore - the charger light just blinks red. I really need this for work tomorrow. Any ideas? Sorry if this is a dumb question, still learning!

Welcome Paul! Not a dumb question at all. Sounds like you might have two separate issues. The grinding noise could be worn planetary gears or a damaged anvil. Have you dropped it recently? As for the battery - blinking red usually means it's detecting a fault. Try cleaning the battery contacts with some isopropyl alcohol. If that doesn't work, the battery might be toast. What's the manufacture date on it? Old Li-ion batteries can just die suddenly.

Ugh, this is why I only buy Milwaukee! Their M18 Fuel impact wrenches have way better durability. But for your Craftsman - Pete's right about cleaning contacts. Also, check if the battery has any swelling. If it does, DO NOT try to charge it - safety first! For the grinding, could be debris in the mechanism. Have you tried blowing it out with compressed air? If it's under warranty, take it to Sears (if they still have service centers near you).

I restore old tools as a hobby. That grinding noise takes me back! Often it's just the hammer mechanism needing lubrication. Try some light machine oil in the impact mechanism (not the motor!). As for the battery - Craftsman's older 20V batteries had known BMS (battery management system) failures. If cleaning doesn't work, you might need a new battery. Pro tip: buy from authorized dealers - lots of counterfeits online that fail quickly.

Thanks everyone! I cleaned the contacts like Pete suggested and the battery started charging! Still blinking but turned green after 10 mins. The grinding is still there though. Carl - I'll try oiling it tonight. Sarah - I wish I could afford Milwaukee lol maybe after my apprenticeship. This has been super helpful - you guys saved my butt for tomorrow's job!