I have a 6x6 norlake walk in freezer. The door

I've worked on freezers for over 20 years and have never heard of a compressor going bad because the door was left open. think about a second opinion.
Also, has the cooling coil inside the box developed and frost or ice build up? If so, it needs to be completely defrosted. If you defrost it manually, use a hose hooked up to hot water. Kill all power and hose all build up off. Remove the sheet metal housing ends and be sure there is no ice inside there too. I would go in this direction first.
IN order to kill a compressor under this condition, something really strange must have happened as anything is possible in a refrigeration system. Good luck and hope this helps.