Sensor disconnection includes leads, plugs and sockets. So you should check whether the socket and lead are normal.
Fault 1, kettle temperature sensor is damaged (thermistor is broken); 2, the main control IC is bad; 3. The oscillating crystal in the pot is damaged;
The corresponding solution to the above problems is: 1. Replace the temperature sensor, with various resistance values around 100K; 2. Replace the main control IC. If there is a program, be sure to contact the manufacturer to buy it; 3. If the linearity of crystal oscillator is damaged, it should be replaced according to the original model, generally 8M crystal oscillator.