Power cycling the printer to get it out of dry run mode seemed to fix it 90% of the time. Once or twice I had to power cycle it again. Thermistor kept reading correctly on the meter. I tested the circuit up to the thermistor bulb itself and back down to the board at every junction and everything looked good.
I had several failed prints yesterday where it would throw a temperature sensor error and go into dry run mode in the middle of the print; at one point I saw a temp reading on the hotend of -20C. Besides THAT, the printer was otherwise running fine when I shut it down and left it that way for the evening.
Turned it on this morning - didn't change a thing - and now the LCD screen on the RAMBo doesn't show anything except four rows of white squares.
HELP
--EDIT / Update--
I've narrowed it down to the hotend thermistor lead. When it is unplugged, the printer boots normally and the LCD display functions, although I get "def" readings for the temps on the hotend AND bed. When it's plugged in, white squares and nothing else. I haven't changed a dang thing since it was working mostly properly yesterday
The thermistor is reading about 100.2k ohms at room temp, which seems off. I have my hotend set up so the thermistor, power, and fan are all on plugs (AND none of them can be accidentally swapped or plugged in wrong, bwahaha). The thermistor shows a good circuit up to the plug, and there's a clean circuit along the lines from the plug all the way down to the board. I'm stumped. Still could use some help here.
