2008 Prius won't start

I have a 2008 that hasn't been used in three months due to the virus. I knew the car was going to be sitting for a while. I had the 12V battery checked and it was fine. The battery is less than three years old. I also turned off the smart key function (at least i am reasonably sure i did). Unknown to me, there was a gps plugged into the 12V outlet but it should have been off. Today I tried starting it and it was dead. Nothing. No interior lights.

I tried jump starting from the rear with no luck. I then tried from the front. I had it hook up to my RAV4 which was idling at a slightly elevated RPM for thirty minutes. When I press power button, the power button led is on, the parking button led is on, the check engine light is on and there is a sound from the dash. That it. No screen, no radio,no fans. The only other thing working is the emergency flashers.

Any ideas? My first thought is that the battery is so drain that even with it hook up to a working car that the voltage is isn't high enough. My second thought is a shorted battery but then the flasher shouldn't work.

Unfortunately all my tools are at home (this is my daughter"s car).

 

I tried again after a couple of hours of the car sitting with being connected to the RAV4 and it is completely dead. I was planning on pulling the battery and fully charging at home (3 hours away).. For future reference can it be charged while in the car?

So the 12V battery can turn the car on?

I am surprise that the main battery could fully discharge in that time period. I also was surprise that the 12V battery was dead after 3 months with the smart key off. What is drawing power? Also why won't it start when connected to a running car?

Normally I would troubleshoot more but the car is in an apartment complex with little access to electric power.

 

Why can't I jump start the car?

 

Thanks. I pulled the battery today. The no-load voltage is 6 volts so it doesn't appear to be shorted. I will try charging it and see if it takes a charge.

Was surprised to see the warning label to not charge the battery an greater than 4 (appropriately) amps for no more than 10 hours. My regular charger is 12A/12v so I guess that is out. I do have a trickle charger that should work over a couple days. I will also check the local shops to see if they will charge at that lower rate.

Is it really possible the main traction battery is too low to start the car. I though the software never allows the battery to go that low.

 

Unfortunately, there is a possibility that the cables were backwards.

I read the manual cover to cover. Never say a warning that the car had to be driven every month. Did see a warning to turn off the smart key of the car was parked for more than two (don't remember) weeks which I did.

 

Okay, looks like the inverter could be fried from reverse polarity. Based on reading here, it is worth checking a few fuses before calling in the pros before giving up. What fuses do I need to check. I know there is a 5A fuse in the back. Looking at the shop manual (Benty), there is a fusable link block in the luggage compartment, What is the procedure for checking that? I assume that can only come from Toyota.

After those two, any advice.

I am handy and a former engineer so I handle the basics. However, I am not keen on going near the high voltage side. I do not have the necessary protective gear.

Based on the repair cost (any idea, I am guessing 600-1000+), I am debating the wisdom of repairing this. The car has 160,000 miles. I guesstimate the car is worth of 2000-3000 (has some cosmetic damage). The AC has a leak and probably needs a evaporator coil ($1600+), the water pump has a minor weepage (350+) the hoses are orginal so thats more (quoted 350-700). Whose knows how long the traction battery last. I have heard 180-200K but varies greatly. That adds 1500-3500.

I love the car but am wondering if the $4000 (not counting the future traction battery cost) is worth it.

 

Thanks. Where is this plug located?