While standing sideways, my left shoulder towards the rear of the car, I pushed the open hatch button. The automatic door began to rise and lifted me up and tossed me against some metal furniture that was behind the car, in the parking lot of a deli. It was over in a second, I couldn't step out of the way because I was holding two bags of firewood, one in each hand, and there was a tall curb, say ten inches high that prevented me from moving quickly out of the way. The automatic return function failed and the power gate just lifted me off my feet and I landed badly on the metal stadium type chairs severely injuring my ribs. It took me a minute to compose myself and rise, shut the hatch and hobble to the drivers door and drive home. The next day I tested the auto return function on the hatch and with the smallest amount of resistance it worked, and auto reversed and closed, multiple times. I could not and can not repeat the failure. I weigh over 250 pounds and am amazed that the hydraulics had that much force to be able to lift me off my feet. My ribs still hurt 2 weeks later but are definitely on the mend. No one witnessed the accident, it may have been captured on video at the store? I have not taken the vehicle anywhere for testing. I believe it may have been raining lightly.