I once ran a subsidiary of Don Simon Homes. We had a thermostat stick in the on position and the temp in the home approached 180 degrees. We had to replace all of the doors (warping) and the plastic windows (the plastic sagged as it got hot.)
It can happen.
When I was a kid, one of our neighbors repaired pianos that had major problems. Most of them were expensive grands that were fire damaged. I remember him telling my dad about a family that went on vacation and the heater (gas) was stuck in the on position for 2 weeks. This was in the late 60s/early 70s. The heat did alot of damage, our neighbor got a lot of work from this home, fixing 2 pianos and other furnature. I remember him showing us a lamp that was melted.
They showed all his melted records and even a plastic table that had been reduced to a puddle on the floor.
At least nobody was hurt in that story. This story is awful.