I discovered an issue where the hotend temperature-sensor pins on the nozzle head board become shorted when the power is turned on. With the power off, the temperature sensor’s resistance can be read normally, but once the power is applied, the sensor pins short to each other.
To further investigate, I performed several tests. When only the temperature sensor was connected to the board, turning on the power and then connecting the heater resulted in the temperature being read normally. This behavior suggests that the short occurs under specific power-on conditions.