It seems that the battery to the smart key ran out. I knew there was what it was called "mechanical key" in the smart key, so I took it out. Great. But..... how can I start the car with mechanical key? And if you are outside, and the door is looked, how could you open the car with the mechanical key. I could find how to use the mechanical key anywhere. And my search for "Mechanical key" in the prius v chat only generated Honda ad..... Your help is greatly appreciated!
Yes, and the battery is the widely available CR2016. It's the same coin battery used in current Timex watches.
The mechanical fits in to the slot in the driver's door handle, just like any key. To start the car, hold the key fob, with the silver Toyota logo, against the Power Key and with the brake pedal depressed, push the Power key and the car will start.