As I understand it, Purism shipped the laptops defective.
See review on youtube:
Go to 1h 20m.
Myself and others have the same problem. The youtube guys tried to troubleshoot it to no success.
Before I saw these reviews, Purism, for some reason, tried to troubleshoot it with me (with no success, obviously, since they already know about this problem), acting like it was a one-off problem, when everyone has this problem. It wasted a lot of my time.
Only solution, for the moment: open up your case, unplug the fan, let laptop run at 65C.