Google Home Won't Mute

Try restarting your device. Open the Google Home app and select the device you are trying to reboot. Go to Settings (three vertical dots in the upper right corner of the device card) and tap More and then Reboot.

or

Unplug the device for roughly a minute, and then it plug back into the power source. Allow the device to reboot itself.

The mute button of your Google Home may be broken or malfunctioning. If this is the case, you will need to replace the mute button switch.