Solved Out of the blue hardware error

Hello everyone!
So, I've had my robo3d for awhile now. I had quite a few issues on start up, but when all those were resolved, it worked fantastic for months with no issues whatsoever. However, when I started it up the other day, I got this message:
"Your printer is reporting a hardware error. This may prevent your printer from functioning properly.
Error reported: ':Extruder switched off. MINTEMP triggered !'"

Anyway, I was looking around at similar error messages online, and so far the only ones that I've found are from brand new printers with a faulty board or a bad thermistor or what not. Now, I haven't made any changes to my printer recently; everything is literally the exact same as when it was working a few days ago. Basically, I haven't got the slightest clue as to whats going on or even how to fix this.

Oh, and just to be clear, the physical problem is that the extruder AND print bed both refuse to heat up. They both consistently read 0 degrees.

 

Well, shit. I started tracing the wires, and I noticed the broken wire. God damnit. I don't suppose you know of an easy way to dig out the rest of the thermistor? I have a spare thermistor that I can use, but it's one of the older models so I'll have to wrap it up in Kapton Tape.

 

You could also install it with the right kind of RTV sealer.

 

Well, either way I need to get the old one out first. Preferably in a way that doesn't break it any more than it already is.

 

There should be a tiny set screw somewhere on the bottom of the heater block holding the thermistor in place.

 

Been there, done that.
The thermister is held in by an allen screw that isn't obvious.
Unscrew it then take needle nose pliers and grab the exposed portion of the thermister (it's a cylinder and is partially sticking out) and working back and forth until it comes out.

The new one should slide right in and be sure to tighten the allen screw to finish it up.

Be CAREFUL of the new thermister's wires, they are VERY fragile!!