The thermal runaway protection cannot protect against a blown MOSFET. It should protect against a faulty thermocouple or thermistor. Stratasys put a resettable thermal fuse on the top of the head specifically for this eventuality. They also put one in the chamber to protect against stuck chamber heaters.

The printers and parts of printers that you buy should, by law, be CE marked in Europe (same thing, different standards for the US) and for the most part they are not. They may display the CE mark but painting it on and adhering to the rules that allow you to paint it on are very different. It is easy to spot things that would never pass the official CE testing.