What temperature is your thermostat set to? Where is the probe, what heat source are you using and where is that? How are you measuring the temperature inside the enclosure?
If you're controlling your heat sources with thermostats, there should have been no way for it to get that hot- it should have turned the heat source off when it exceeded its set temperature. It sounds like your thermostat may have failed, in which case it's time for a new one.
Sent from my XT1080 using Tapatalk