Sorry for the delayed response but thanks for posting. Let's further check on your thermostat.
A few questions — does your thermostat display show a message or a code? When trying to reconnect it back to your Wi-Fi network, are you getting specific codes or message on your Nest app? Also, were there recent changes made it's setup or on your Wi-Fi network?
Please go through the suggested troubleshooting steps here then let me know what happens.