GM and dealerships tell customers to pound sand all the time. Even if it’s UL listed that doesn’t gaurentee that singular unit isn’t defective.Is the Mustart unit UL approved? If so, then Chevy can't tell you it is unsafe to use for charging of your car and deny the warranty repair. If they want to sue Mustart for the damages that is their business. If the Mustart unit is NOT UL approved then it becomes much harder.
If I recall another forum member recently got mustart to pay for similar damages. I think there was a mustart customer service rep quasi-spamming the thread with apologies and claims about a bad batch of EVSEs.