This post on the problem at Cloudy Nights is quite illuminating (warning: after you read that entire Cloudy Nights thread, you may never buy another ZWO camera; paste leaking, sensor window cracking, USB connect problems):
https://www.cloudynights.com/topic/739425-zwo-asi2600-mc-issues/?p=11147290
The gist is the problem appears to be caused by the low quality of thermal paste. Extreme low temperatures apparently caused the oil to separate with a large temperature change.
For what its worth, I have never driven my two 2600 (a Bayer and a mono) below -15ºC. I don't know if that is why the two have survived so far. Perhaps ZWO can give us the specs of the thermal paste used.
Unless ZWO has changed to a different thermal paste, any "solution" may just be a placebo. ZWO's answer to this problem (on this forum) appears to indicate that they think it is a QA problem, not their choice of paste.
Secondly, based on the Cloudy Night thread, at least some US dealers will clean the camera for you. This is why establishing a good personal relationship with a good dealer is important. ZWO may give you a hard time before issuing an RMA, but a friendly dealer who know you personally will help as much as they could.
A customer should not be required to do this themselves. It is not what they signed up for.
Chen
EDIT: check another thread on this forum on tilt that multiple people are seeing. What a train wreck of a camera.