I saw that the other day and what I can tell you is that those freezers typically have temp limit alarms on them. Anytime the temp rises to a certain point, a point usually just below the critical temp point, the alarm goes off and usually someone is called to alert them to the rising temperature. It seems this facility did not have proper SOP or alert systems in place on how to handle such issues. The other is that the reason they gave of "a door not closed" is a lie. If you have ever seen such deep freezers, you will know that these aren't your typical boxes with a flimsy door. They have specific lock apparatuses that are lever like in most cases and are hard to ignore.

I know because I have many years using Revco deep freezers (-85.0C). and walk in freezers with ante rooms at -36C where human plasma bottles after collection is stored.