Centauri Carbon Microswiss hotend malfunction

Swapped my factory hotend with a Microswiss one. Recalibrated, no issues, ran through a fillament calibration routine, no problems. Loaded in some Elegoo PLA-CF to print a snap lock box, and it printed the bottom half model no problem, but then about half way through the other half, it turned into a spaghetti mess and failed. Now whenever I power on the printer the nozzle temp heads for the sun, even though the set temp is zero and it reaches 350 and then the printer failsafes. Is the Microswiss hot end FUBAR'd? Waiting for it to cool off before I swap the factory one back in.