/diy/ - Do It Yourself

There's a MK2S at work which I've been vaguely tasked with fixing. Cleared a jam in it which made it start extruding again but now there's an issue with thermal runaway. What's the most likely culprit, thermistor, hotend, or something else? Is it worth it to try and diagnose or is the part(s) cheap enough that I can just throw it out and buy a whole new heater block/thermistor/nozzle/etc. assembly? Pic related isn't mine but is same error.