I do not think the sensor is defect, it must be somewhere at the input on the charger. Just looked at is and pretty stupid to use a same JST-XH connector for the temp sensor but on the other hand it is also stupid to plug the balance connector to it. That it did happen before tells me it is not easy to blow up something so probably not the processor. You need to open the charger and look around the connector if you can see something burned.