I applaud this effort! Smart. I've had some close calls where, for instance, the extruder fan knocked itself off, so the ABS solidified in the fin/hot/cool end. I don't quite get the theory around why this happens when it's too hot (I can understand if it's too cold), but I would have thought that too hot would liquify the ABS, but there you go.
I have a Monoprice Mini Select v2 with v40 firmware, and I'm pretty sure that it has thermal runaway protection.
Here was the situation, I changed hot end aluminum blocks and thought that I did a good job of securing the thermistor. I was wrong. For the next print, the thermistor dislodged itself from the block, so of course, it was measuring the ambient temp outside of the block.
My extruder was never going to get to the 240 degC that I'd specified if the measurement was happening outside the block. Eventually, Octoprint detected the error and spit out the following in its logs:
Offline (Error: Heating failed, system stopped! Heater_ID: 0.
Looks like it worked to me. The MP Mini Select at least reported the error, and OctoPrint detected it and then shut down the process.
Does this help? I can run a dedicated and more controlled experiment if you want.