Help! My rotary tool's battery won't charge and it's making a weird noise

Hey everyone, I'm having a weird issue with my cordless rotary tool (brand: ProSpin). The battery won't charge at all - the charger light just blinks red. When I try to use it anyway (it had a bit of juice left), it makes this high-pitched whining noise and then stalls under light load. I was just trying to polish some metal brackets. Any ideas what's going on? Is this a common problem?

Classic battery failure symptoms! That blinking red light usually means the charger's detecting a bad cell or the BMS (battery management system) is fried. The whining noise before stalling is probably the motor struggling with low voltage. I've seen this a dozen times with lithium-ion packs. First, try cleaning the battery contacts on both the tool and charger with isopropyl alcohol - corrosion can cause false errors. If that doesn't work, you might need to crack open the battery pack (CAREFULLY!) and check for swollen cells. ProSpin uses standard 18650s - you can replace them if you're comfortable with soldering. Otherwise, time for a new battery.

Whoa whoa, don't go opening battery packs unless you know what you're doing! That's how you start fires. Before anything fancy, try the cheap fixes: 1) Leave the battery on the charger for 24+ hours - sometimes they need a super slow trickle to wake up dead cells. 2) Check if ProSpin has a warranty - some brands cover batteries for 2 years. 3) Look for generic replacement batteries on Amazon - way cheaper than OEM. I got a compatible one for my rotary tool for $25 vs. $80 from the manufacturer. Works fine for 6 months now!

The stalling under light load concerns me more than the battery issue. Even with a weak battery, a quality rotary tool should maintain consistent RPM until completely dead. That whining noise suggests possible bearing wear or armature problems. What model ProSpin exactly? Their 2020-2022 models had known brushless motor controller issues. Before investing in a new battery, borrow a known-good battery from a friend to test. If it still whines/stalls, the problem is in the tool itself. For precision work, you can't have erratic performance - consider sending it for professional service or replacing if it's the faulty generation.

Thanks all! It's a ProSpin RT-3400 (bought early 2021). Good tips - I'll try cleaning contacts first, then the long charge. If that fails, I'll see if my neighbor has a compatible battery to test Rick's theory. Appreciate the warnings about opening batteries too - not my skill set! Will update tomorrow after testing.