Done it twice myself, both times while deliriously tired. First time I was hosting a meet and it was about 4 am, and I forget what board it was, but I had a MAK rapid fire unit hooked up on a Supergun. Knew it was bad when I heard something hit the wall. Yep, blew a transistor off the rapid fire unit, but got it fixed and it still works. Another time I had got home from work and dinner super late, but wanted to try out the board I just got. Plug it in and see the voltmeter look all kinds of screwy and was like OH CRAP. That board was Double Wings, but it is still ok. I finally just took my label maker and put TOP on all my harnesses. Idiot proofing for my own sake.