All of a sudden when I try and start a print, after 10 seconds after starting the first layer the extruder temp flashes a negative number quick than goes undefined, BUT it will preheat at those same temps for a long time without erroring...

my printer had a melzi 2.0 red board in it

video: https://photos.app.goo.gl/wKOcFyhE5CVSAzlM2