2011 Prius won’t start: dead 12v battery?

Hi all,

My 2011 was fine yesterday. Today, less than 24 hours later, it won’t start. I’ve tried researching on my own and (pure guess), I’m leaning toward the 12v battery being the problem. Hopefully, someone here can point me in the direction of the issue and the fix. Never had any battery issues or had to replace the batteries in the 10 years I’ve had the car. Here’re the symptoms.
-Power button starts orange and turns to red.
-Engine won’t start, engine icon won’t come on screen.
-During my first few attempts to power on, all the warning lights came on and staid lit. Everything lit up on the screen except for the engine. If I left it on for more than a minute or two, I’d lose power completely. On more recent tries, only the check engine light comes on and, sometimes, the caution triangle on the left. It also is taking longer and longer for anything to light up each time I try to start.

Any help or advice is appreciated!

 

Thanks. Seems like I was damned lucky to have it last that long. Any recommendations for a replacement battery beyond trying at a dealership?