Please help - dead 12v battery?

I just bought a 2004 Prius from a dealer. This is the first car I have ever owned. I drove it from the dealer to our home yesterday where it is now parked.

Today, I when out to look at it I found that the central locking didn't work and after some googling I opened the door with the metal key inside the fob.

Once inside, the car won't start. I suspect the 12v battery is dead, possibly because something was draining it. I had put a usb charger into the cigarette lighter socket in the central console. Secondly, I noticed that I had set the dome light switch to "DOOR".

What now? What might have caused it? One complicating factor is that I don't know anyone else who owns a car so there is no one I can ask for a jumpstart (if that's even what I need).

Thanks in advance.

 

I'm in the UK

 

Thanks for all the suggestions!

I don't know how long the car sat on the dealers lot. I would say at least a month, over the Christmas period.

I didn't see the dealer jumpstart the car and it wasn't running when I got there (though they did know what time I was coming).

The dealer is about a 45 minute drive or a 90 minute ride on public transport.

I don't have a jump pack. I could order one from Amazon - this one looks like the right thing:

I don't have a digital multimeter either I'm afraid.

I paid by credit card. There are some rights in the UK when you've bought from a dealer:

The second-hand car I bought has a problem, what are my rights?

I can give them a ring tomorrow morning and try to make them drive in and fix the problem. Better yet, maybe I can convince them that the 12v battery needs to be replaced, though it seems like the Prius doesn't use the normal kind.

 

Thanks again for all of the responses. Here's an update:

I've spoken to the dealer. He says that the battery worked fine when he had it. ("Well he would say that, wouldn't he?").

I've found a multi-meter deep in the attic, but it doesn't have banana clips. Shops that sell those open Monday so I'll go and get some then. That will allow me to test whether the battery is dead or not.

I've ordered a jump kit online with express delivery. This one:

My plan is to jump it using the fuse box section under the bonnet (though the battery itself is apparently in the rear).

I'll try that tomorrow (Sunday) and see if we can still go on the day trip my wife and I were planning on.

I happen to have a warranty. It's not clear whether this covers a replacement of the 12v battery. The dealer expressed doubt on the phone. Can't start working on that one until Monday as well due to phone lines being closed.

My current plan in short: jump it tomorrow AM, drive it the 1 hour journey for the day trip. See if I have to jump start it again at the other end. If I do end up having to get the battery replaced, I'll try and claim it on the warranty but if I fail I'll try to do a partial chargeback against the dealer for the cost of it.

Please let me know if this sounds like a good idea! I'm don't have any experience with cars and one of the quirks of my local area is that very few people own and drive cars so you are all coming in really handy.

 

Yes, I do have two fobs, both work (or at least, they did before the battery was dead ).

It's true, I do have a lot of rights. At this point things are a little unclear because it could be my fault - if I'd left the dome light on or something. I don't think I did but I don't think I can really rule that out until I know the problem recurs even when I've turned everything off. Being able to use the multimeter should narrow it down a lot too - if the voltage is low then I think my case will be clear cut.

Thanks a lot for the links to how to test the voltage in maintainance mode. All this stuff really helps and is really appreciated. I would be totally at sea if you weren't responding!

 

Unfortunately this won't be possible for me. The only place I have to park this thing is on a the street outside my flat in Central London. Apart from the danger of someone stealing it I'll probably get fined if I do this because of the rules about emissions and engine idling here.