Dead thermister or dead board on Ender 5? I have a base model Ender 5 with the silent v4.2.7 board.
Earlier this week during an overnight print, I came in to find it unfinished and powered off. I turned it back and it complained about an outage. When I started warming the hotend, it squealed and turned itself back off and then back on.
Now anytime, I try to warm up the hotend, I get the same.
I set up the printer to give data me debugging data via the console in Pronterface and in Simplify3D. I don't receive any kind of error, the printer just powers off and then back on.
I'm hoping that the thermister is just dead and I can replace it easily enough. What I'm afraid of is that the board itself is dead. BTW, I am able to warm up the bed with no problem, just not the hot end. Any insight would be appreciated.
&quot;Heater core&quot; wires are not the same as thermistor wires, are they?
Check if thermistor is properly connected?
Reading -14 C in my case always pointed a disconnection of thermistor. (I didn't had a case of broken one so far.) In case of short it would probably show som max temperature (my guess, I dont want to try), but it is always good to check if wires are do not touch each other and are properly insulated?
Measure thermistor's resistance
If you are able to use multimeter, then:

disconnect thermistor from the printer board
set multimeter to resistance measurement (200k Ohms)
connect thermistor and multimeter using wires - the ones having aligator clips would be the best
read resistance measurent

My spare shows 97k Ohms in room conditions. So value should be high (you may refer to specs sheet of given type when in doubt).
Check that hotend is actually powered
If thermistor is OK, then indeed the hotend powering may be broken. Ths definitely require skills and may introduce many risks to electronics and maybe even to your health - but if you are skilled enough, you may measure with voltmeter if there is correct voltage provided to the hotend. For example the MOSFET on the board may be broken (I already replaced one in the past for my heated bed).