When you finish using an electric screwdriver, be it only for a couple of minutes, always leave it set to drive. I just now learnt this after spending five minutes in a stress position, getting a screw between almost inaccessible part A lined up and engaged in invisible and wanting to bugger off part B and then merrily unscrewing it. And when I pulled the driver back the screw came with and everything went zonk. Language ensued.