Appliance dolly to the top of the deck stairs then straps the rest of the way. A good dolly leaves no marks on the floor or the appliance moved. Pool noodles on the vertical rails to protect the appliance and a good dolly will have V-Belts at the bottom to eliminate damage to the steps. I've used the straps and they're a huge pain on more than 2 or 3 stairs. The outcome here was inevitable given the amount of stairs and apparent lack of experience.