If your speaker stops responding, has Wi-Fi issues, or needs a fresh setup, learning how to factory reset Google Home Mini can help. First, keep the device plugged in and turn it upside down. Find the small reset button below the power cable and press and hold it for five seconds. 

Continue holding for about 10 more seconds until you hear a sound confirming the reset. Once complete, the speaker returns to its original settings, and you can set it up again using the Google Home app. Remember that a factory reset erases device data and cannot be undone. Source: Official Google Nest Help.