I would think that a trip to "The Dead Mac Scrolls" might be in order. I'd look it up myself, but I'm at work and the book is at home. Failing that, Macintosh Repair and Upgrade Secrets might cover such a failure, but it is less likely.

Actually, as I recall, Apple did strenuously recommend against hot-plugging ADB devices. My guess is that if you plug/unplug it too quickly, the step function change in current causes a voltage spike which kills something.