My two Wyze door sensors needed a battery replacement. I ordered a card with two button batteries from Amazon and did the replacement. One sensor came back online without any issues. The other would not connect to the Wyze hub. Removed the sensor and tried to reinstall it. Would not work. Thinking I had somehow not replaced the battery (put the old one back in) I ordered another two pack of batteries which arrived today. Put in a fresh battery and still nothing. Rebooted the wireless router and played with the network connection. No good. Finally I restarted the Wyze Cam with the hub in it (software reboot) and after that the sensor connected immediately. Wyze should include restarting the Wyze Cam/hub in their suggestions.