I got two voltage regulators from John on Friday, and I installed one this morning, but I’m still getting the same result as before: plug into computer, nothing at all happens and Windows doesn’t detect anything. The lights come on, which is promising, but not especially helpful. Given that a new board is only $12 on Amazon, I’ll probably go that route and just not plug in the steppers the wrong way this time.
Or pay the stupid tax for something else. We’ll see.
Thanks for your help, guys!