Hatchback/liftgate problems of the 2010 Cadillac CTS

I used the remote to open the power liftgate. I leaned into the back of the wagon to retrieve something, and the liftgate crashed down onto my back. It lifted back up, and then crashed down again. I was able to get out of the way, and the process was repeated until I manually slammed the liftgate closed. I opened it again with the remote, and the same process occurred. I changed the setting of the liftgate to manual and lifted it myself, and again it crashed down. It bruised my back and shoulder, but could have done grievous harm to someone else. I am taking it to the dealer tomorrow.