Open the door to thaw tube (I hang a moving blanket to keep the freezer cold). A turkey baster and really hot water or a steamer might help. After it's thawed install the heater kit (if your freezer has a metal lining) or just leave the light on. The light should put out enough heat to keep it thawed.
is the correct kit, if you have a metal lined freezer. I usually order and replace the Bezel too as the frame can be difficult to remove without breaking a couple of the plastic tabs that hold it in. YMMV.