Depends on the plastic, you can safely heat most polypropylene and polyethylene based plastics. If it’s putting off noxious fumes then it probably has urethane, styrene, or vinyl in it.
The worst plastic to overheat that I’ve worked with is kydex. Even though it’s most common application is as a thermoplastic, if you over heat it the stuff off gasses hydrogen chloride.
I can vouch for reolink, they have fairly straight forward nvr with decent cameras for the money. Been using their poe nvr system for around 5 years now and have never had an issue with it.