My door sticks opening after couple of hours and definitely cold mornings. This happens when I try to do it manually or with opener engaged. It’s literally jammed. My 8 year old son can put a shovel at the bottom of the door and stand on it and it will click and free up. Literally .25 inches from initial force and then it’s fine. After initial opening it will behave the way it’s supposed to for 15 mins to all day if it’s a warm day.
If your son is prying up with a shovel to break it loose is it freezing the rubber seal to the ground. On rubber seals on my truck doors I spray them with Pam cooking spray and they don't stick when frozen. This may also work on the seal at the ground. It's worth a try.