Immersion blender BRAUN type 4130 fault

Hi, I’ve an Immersion blender BRAUN type 4130
By pressing the top button on the handle (to give consens to the main switch to run device) the LED lights up red. This means overheating error even if the blender is cold as an ice piece. The 7.4v rechargeable battery is good and connecting it directly to the CC motor this one rotate normally. The positive clamp of CC motor is connected to the battery positive pole by the main switch but the negative plug is connect to negative of battery (ground of pcb) by a MOSFET FDD8896 (source on ground, drain on motor negative pole and source to the control circuit). Between drain and source there is a component ( surface-mount device as all the others) without any code printed, I guess it’s a Negative Temperature Coefficient resistor ’cause heating it by an hair dryer the resistance decrases from 145 kohm to 25 Kohm. Does anyone know if these values are in line with this kind of circuit. The resistance could be wrong and give a wrong information about the temperature device.