Before you do anything, check the voltage of the 12V battery in the back of the car. It should read 12.4 and above with the car off and 13.8 or so with the "ready" symbol on. If it's showing anything in the 11V range or lower it may be shot although it may be just low on electrolyte.
These often die on the Prius and can cause all kinds of strange error messages. The 12 volt battery can be replaced with a non Toyota battery more cheaply from an auto parts supplier. The fact that the car runs means that the 12V system is getting power from the DC-DC converter. If you can clear the code with your scanguage do that and see if it happens again.
The dealership blaming you without evidence is a nasty tactic. There are many cases of the dealership just throwing parts at a problem without diagnosing properly. They like to sell you their expensive parts.
Please go to Prius chat where there are many expert people who can help you.
PriusChat Forums
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Vortex generators are old tech. My new and improved vortex alternators are unstoppable.
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