It happened again. Dianne and I were on our way to a CPR course. GPS had no voice prompts, because it was running off its internal battery, just like in San Francisco recently.
When at our destination, I used a small Allen key to remove the battery completely. This does a reset. And then...
Back in the cradle, the GPS worked normally, off the vehicle battery.
I could have done this in CA, if I had thought of it. I always carry the hex key... .