I used to have a B&D dustbuster/vacuum combo that ended up the same way after sitting a while. Like you, I wanted to swap out the battery but the internals were so convoluted my odds of just destroying it anyways were pretty high.

I have a Craftsman 20v toolkit and they make a dustbuster/vacuum that takes that battery. It’s pricey at $200 but most anything would be better than my wife’s expensive RoboRock vacuum. It gets clogged moments into trying to vacuum carpet, granted its pet hair. Its no wonder they only do the robo-vacuums now.

I usually end up using my little handheld that I bought for around my desk for small messes or the corded Eureka for bigger cleanups, though that is a pain to lug up and down the floors. Hence looking at the Craftsman.

The Hoover OnePwr series has external batteries, like you find on power tools.

Plus you can buy replacements and larger capacity batteries on Amazon.

if there was more people here someone would have recommended a Dyson not knowing what their talking about.

Dustbusters have been dying an early programed death for decades now, going back to the NiCad battery days at least. Please don't buy another one.