Diagnosis
The speaker has lost its Wi-Fi connection and is in setup mode. A spinning orange light means it's ready to be configured or is trying to reconnect.
How to Fix It
Open the Google Home app on your phone. If the Nest Mini shows as "Offline," tap on it, go to Settings > Wi-Fi, and select "Reconnect to Wi-Fi." Follow the in-app prompts. Ensure your phone is on the same Wi-Fi network you want the speaker to use.
If That Didn't Work
Your home network may have changed. Perform a factory reset by pressing and holding the center of the device for about 15 seconds until you hear a confirmation sound. The light will then pulse blue, indicating it's ready for a completely new setup in the Google Home app.
Heads Up
After a router reboot or password change, your other devices may reconnect automatically, but Nest devices often need to be manually reconnected through the app.