When I first saw the dragonfly lying in my yard I thought it was dead because it was dry, stiff, crawling with ants, and totally unresponsive to being picked up. I brought the dragonfly inside so I could preserve it, but half an hour later it started making very lethargic movements. I then put it back outside, took a few photos, and then left the reviving dragonfly to its fate.
 
I had a similar experience with another Aeshna darner last week. This one I found in the water apparently drowned. I fished the dragonfly out of the water and then brought it inside to let it dry out. The dragonfly was limp, waterlogged, and showed no signs of life whatsoever. My plan was to identify it and take super macro photos later in the day. Six hours later, when I was sitting by the back door reading a book, I heard a buzzing sound coming from the window sill where I left the dragonfly. To my amazement the dragonfly was alive and trying to fly! I brought the dragonfly outside, put it on the deck railing, and it then flew off good as new!