My cordless drill's battery won't charge - any ideas?

Hey all, I've got a problem. My cordless drill's battery won't charge. I've tried plugging it in and leaving it overnight, but the charger just shows a red blinking light. It's an older model, maybe 5 years old. Any thoughts on what could be wrong? I'm not sure if it's worth trying to fix or if I should just get a new battery.

Could be the battery cells are dead. Lithium-ion batteries don't last forever, especially if you've left it fully discharged for a while. If it's a 5-year-old, it might be time for a new battery. But before you do, check the charger itself - sometimes the charger contacts get dirty or the charger dies. Try cleaning the contacts with a bit of alcohol and a q-tip. Also, make sure it's the right charger for that battery. If it's still blinking, I'd say the battery is toast.

I had a similar issue once, and it turned out the battery had a broken wire inside. Took it apart and there was a loose connection. If you're handy, you could crack it open and have a look. But be careful with lithium cells - they can be dangerous if punctured. If you're not comfortable, just buy a new one. Or if it's an older drill, maybe consider upgrading the whole tool - sometimes you can find deals on a kit with batteries.

Before you toss it, check the voltage with a multimeter. If it reads like 0 or very low, the battery is likely dead. But if it reads something, maybe it's just the charger. Also, some chargers have a 'refresh' mode or you can try a 'battery revive' method by charging it with a higher voltage briefly - but that's risky. If it's a decent brand, they often have a warranty or replacement program. But honestly, for a 5-year-old battery, just replace it. You'll get more peace of mind.