Not a pro either, but I guess the risk, for an unplugged device, is about capacitor: they store current, and if you touch both ends of big one close to the alimentation, you are going to have a nasty shock.<p>I had first hand experience of that: I repaired a screen, plugged it in to check it, then unplugged it and realized I forgot to cut the ends of a capacitor. When I touched it with a metal tool (luckily, the tool was insolated), there was some serious spark, that I guessed where due to capacitor discharge. Had I used my hand, this would have gone through my skin instead.