I forgot I was using a VPN on my tablet and somehow reset the living room Google Home Mini as belonging in another home, supposedly owned by just Jay. The device no longer knew who I was. That felt as if my friend could not recognize me. Jay could no longer control this apartment's wifi controlled lights and plugs.
So today, I learned how to do a factory-default reset on a Google Mini. Getting it back online took only minutes.
The tiny button sits on the bottom near the the power cord input.