What Have I Done? (Cannot start or jump 2010 Prius)

I have a 2010 Prius III with an aftermarket stereo by Kenwood. I was having some problems with the speakers cutting out after driving for awhile so I opened it up to diagnose. I completely forgot to disconnect the negative terminal before disconnecting the stereo .

After plugging it back in it worked fine and got sound but then after a second time trying to power up, the dash lights all started flickering on and off, and so did the stereo. I then got a "There is a problem with the transmission 'P' lock mechanism" error. I attempted to restart a couple times but couldn't get it off the screen.

Now nothing will start up. All I hear is the high pitched whine from under the hood and I see a flashing red light with a lock & car which I think signals the alarm is active. I think the whine is from some kind of AC or cooling pump but normally when I shut off the car it does too after a few seconds. Now it doesn't shut off and the 12v battery is acting like it's really weak.

I've tried disconnecting the terminals and leaving them off for a while to reset the codes. I've also tried jump starting (made sure polarity was correct) and I've tried the emergency hybrid startup mode and maintenance mode. Nothing seems to work and I cannot get to the ready screen. I've checked several fuses which I thought could be blown and they all seem fine. What else should I look for...really concerned that I fubar'd my ride!

 

I'm not entirely sure, just bought it a few months ago. Even if it is the 12 volt...I should be able to bypass it via jump start or emergency mode to get to the ready screen right?

 

Thanks for the replies! As to the emergency mode, I'm referring to the procedure laid out in this post:

Prius won't start...ready sign never turns on | PriusChat

Are there any other special precautions for jumping a prius. I know that a polarity mismatch can really hose it and they say not to rev a car up either. However, I'm using one of those portable battery starters, is there a specific amp limit or requirement for those?

 

Unfortunately I can't get it to jump. If I disconnect the negative, I get absolutely nothing. I know the charger is good and is full. I tried both jumping it directly from the battery terminal and also in the front under the fuse box.

I did verify though that the 12v is original so I'll be ordering a new one. I wonder if a weak 12V could be the reason I was having problems with my stereo? I have a Prius with JBL speakers...does the 12v help supply any power to the amp? The problem I was having was that after driving for about 5 minutes, the sound would suddenly cut out of everything except the back speakers. The front would then intermittently cut in and out. I know it wasn't a wiring issue as it had nothing to do with if I hit a bump or rough patch or anything and it didn't sound at all like a bad connection. It was more like the amp simply stopped supplying power to some of the speakers. Plus it would be fine after I let it sit for an hour or so, only to cut out again exactly 5 minutes after starting. Well hopefully this will fix the issue, but I am a little concerned that I am unable to jump the Prius, should I need to in case of emergency!

 

Yeah I know the jumper is good...I used it on my Grandma's car just a couple weeks back and then charged it again directly after.

After letting it sit for a while, I was able to get it in ACC mode, but can tell the charge is still very weak as all the lights are flickering on and off and dome light is dim. Once I try starting though, it immediately loses all power and I only hear the pump running. I think I'll take the battery in and see if it's still got any load or not. Thanks for the assistance!

As for fuses, I checked most I thought to be pertinent to the problem and they looked good. I think Gen 2 Priuses had a fuse right by the battery terminal. I couldn't find any though so not sure if that still exists on Gen 3.