DRM feels like conjecture. You admitted to working on it, it's also possible you broke it / didn't hook it up correctly?

Maybe, but I also know how to measure voltages, and everything was fine.

Except, I guess: It didn't work, so it wasn't fine.

I mean, if you want to think I broke it, you're free to. The fact remains that my battery connections were correct, the voltages were right, but the vacuum didn't work with either the battery I made or the new one I bought.