Sound like a you have a door seal problem, if you get warm air in a freezer for too long will cause the air to crystalize and look like someone took a snow blower and blow it inside. Simple repair is to empty unit a unplug unit to thaw completely, but this could take 24 hours or so to do this. and towels inside unit to prevent leaking on to the floor. Either way you need to remove the frost so the unit will start working again.
After clearing the ice out, you will restore air flow inside the unit and things should return to normal, also check door seal to assure complete seal is made to prevent this in the future..
Good luck, be-careful it can contain all lot of water, for water the floor..... I’m happy to help further over the phone at https://www.6ya.com/expert/gere_bf68e6055dd61249