Hi there, we are very sorry to hear your sensor has run into some trouble with the battery. If the battery dies in a sensor it may be unable to connect to the bridge even when replaced with a new battery. If your sensor is still unable to connect even after replacing with a new battery, please reach out to our Wizards team (https://wyzelabs.zendesk.com/hc/en-us) so we may help out. You may tap on the Message icon in the bottom right hand corner of the support site > fill out the questionnaire > choose the way in which you would like to speak with our team. Please include as much information on your issue as possible. Our products come with a 1-year manufacturer warranty, so if the device is determined to be defective we will be happy to exchange it for you. Thank you for your feedback and have a great day!