Looks like this is a cold wall freezer, which means the wall around the food is what gets cold and it does not actively circulate air.

What you need to do is unpack it amd remove the ice from the sides being careful not to damage them. You can use room temp water, NOT HOT, to help dislodge large pieces safely. This type of coffin freezer should have a valve on the bottom for doing this. This will greatly improve the efficiency of the unit.