2007 Prius sometimes doesn't start (after a few tries, it works)

Hi folks,

Video to show what's happening photos.app.goo.gl/AyjV1j1mLCuhQQ589
I have a 2007 Prius and It seems to be having this problem more frequently now for the last year. Once in a while it won't start and shows the red warning icon and the infotainment screen also does not turn on. Pressing the power button a few more times does nothing. After waiting for a couple of minutes, if I try again it seems to work.
Just worried that it's getting worse and worse since now it happens once every 10 / 15 times.
Is it a computer problem? I took it to one shop and he said it could be a hybrid battery issue but that seems wrong.
Any advice would be helpful before the car turns into a brick!
Thanks

 

The battery is not too old but I have not checked it with a multimeter. I will do that as well. Thanks

 

Thanks for the help. !

Battery reads 11.5v after 3-4 days of not driving. Is that bad already?
Battery is 3 years old and I usually drive 20-40 miles a week.
I looked at the manual and can't really make sense of what the error is supposed to be ... I posted the video above (can't make it a link), so hopefully some one can take a look?
I'm in Sunnyvale in California in case there are ppl around me.

Thanks!!

 

No I just bought it from Amazon. Wow didn't realize 11.5 would be low. Thanks!!

 

To be specific I bought this battery which had 2-year warranty and now I'm in the third year:
ACDelco Gold B24R 24 Month Warranty Hybrid Vehicle AGM BCI Group 51 Battery