Not starting, weired system status

This morning when I sit in my prius, engaged brake and pressed ON, I was surprised that the car was not starting. In fact in was in a status between OFF and IG-ON mode. The cabin lights were on, so as the head lights. The dash was lighted, but weird: the fuel indicator shown empty, though it was filled two days ago and the central screen was not lighted, so it was not the IG-ON mode in which the central screen should be lighted. I cannot switch from the P mode, and I don't remember whether I saw the "ready" on the dash. I turned the system OFF and repeated the procedure but it was on the same situation.

I was a bit panic, looking at the manual and after few minuets I decided to try again. And surprisingly it backed to normal. I drove it all the way to work and didn't notice anything wrong.

So it seems not to be a 12V problem, as the dash was partly lighted. I was driving my second-hand 2008 prius for 7 months and it was all fine despite a minor issue (the back camera is not working one in ten occasions). The car was in the garage for just overnight, and when I finally able to turn it on, the HV battery was well charged.

Does anyone had a similar experience? I would like to know if it was just an incident or it actually indicate some more severe problems?

 

Thanks a lot for the suggestion. Indeed it was the problem of the 12V.

After parked for 8 hours I got the same error while trying to start my prius. I kept the car in the "error" mode for a minuet (during which the dash was lighted and I saw the triangle sign), I then successfully restarted it. Entering the ACC mode and the voltage was just 10.0 V! and it was keep dropping, in few seconds it was dropped to 9.5 V.

I guess the 12V was not completely dead, and even though at beginning it was not able to wake the whole system, at least the HV battery was able to charge it. Now my question is how I gonna to deal with it? Is there a chance that the 12V was just drained and may be charged back to normal after a while (or few hours as someone said), or that simply means that I have to replace it?

 

While reading I just realized the rear dome light is ON! Must be my friends who turned it to always ON position yesterday. It's a shame that it was not designed to off after say one hour.

I'm going to let it charge for few hours and hope this will solve the problem.