Have Toyota Questions? Ask a Mechanic for Answers ASAP
Thank you for allowing me to help you with this concern today and am sorry to hear that this is happening. I will have to ask you a few questions so that I can get a better understanding as to what may be going on with your Prius.
The flashing light you are seeing is the Immobilizer light and from what you are describing, it is operating normally. Here is a quick video explaining the light and how, when you are not in the vehicle, will act as a warning to potential thieves to avoid your Prius as it's not an easy target. Here is the video..
Does this make sense?