Dodged a bullet

Was going to print a case for the esp32-cam that I finally got to work (by buying a new one)

I sent the print to the printer, pre-heated the bed, waited a few minutes for the chamber to heat up, then started the print

Now, typically, one should be physically present and watching the first layer of the print to make sure that it's working, but, after doing this for a few years, one gets slightly jaded, overconfident even

All I did was hit start on the print from upstairs, and didn't bother to even look at the camera to make sure it was working, cuz, of course it was working. Why wouldn't it be ?

An hour later I decided to check on it, and Octo-Print had a red error message on it. It was vague, so I just remotely restarted the printer and OctoPrint, waited for it to come back up, and this time, the error came up instantly

Rats. That can only mean that there's an actual problem, so I went downstairs, opened up the chamber, and saw that the whole of the extruder module was covered in a white/brown fine powder

Just in case you were wondering, no, that's not normal

The thing that gave away what the problem was was the LCD screen saying "def" where the temp should have been listed. I've run into this problem before, and it means that the thermistor had come disconnected. So I looked, and sure enough, the thermistor for the hot end had come unplugged from the controller board

Now THAT was odd. How in the heck did a wire come unplugged ???

I reconnected it, and the LCD behaved properly, so I started a preheat, only this time, I stayed to watch it. The preheat worked, so I hit start on the print. I'm printing PETG on this printer, so mine is set for 238C, and I sat there and watched it get up to 215C... and stop right there. It never got any hotter... WHY ?

I turned everything off, opened up the chamber, and started poking around, and finally found that the thermistor had popped out of the heat block. This means that the temp that it was reading was because it was merely in close proximity to the heat block, but not actually touching it, which means that the heat block, in order for the thermistor to read 215C, must've been quite a bit hotter than 215C. Like, A LOT hotter

Hot enough to turn the filament and the PTFE tubing into white ash

Unfortunately, I pulled it off before I took a picture of it, but, here's the twist...

If that wire hadn't come unplugged, that heater would have just stayed on, and tried to do every thing it could to get up to 238C, probably starting a fire at some point. When that wire came unplugged, the safety features kicked in and turned the whole unit off

The wire didn't break.

It didn't melt near the heat block

It came unplugged from the controller, as if somebody walked up and unplugged it

Totally bizarre and impossible

And lucky