Dead Battery Won't Jumpstart

Another 12v dead battery question, although I did a search and couldn't find anything about this particular problem. I have a 2007 Prius Package Six. I went away on vacation over Christmas and when I got back the battery was dead and the car wouldn't start. No problem as I was easily able to jumpstart it with a portable battery jumpstarter. However I kept having the same problem as apparently the battery wasn't maintaining a charge. So obviously my battery is kaput and needs replacing. I've watched the videos and plan on replacing it myself.

However when I went out this morning to jumpstart the car it wouldn't jumpstart at all. When I hook up my battery jumpstarter nothing happens. Nothing lights up. The car won't start. Even if my 12v battery is completely dead and cannot maintain a charge, shouldn't I still be able to get the car started with a jumpstart? I realize that as soon as I turn it off I will have to jumpstart again. But I can't figure out why a jumpstart won't even get the car fired up

Am I missing something? Do I have a bigger problem? Help!!!!


UPDATE!

After I posted this I went out and tried again. I should have been a little more clear in my last post. When I hook up the jumpers the car would light up but as soon as I unplugged the jumpers all went dead. Apparently my problem was that I wasn't leaving the jumpers on long enough for the car to run through some computer stuff so I left them hooked for about 5 minutes and then the car started. I didn't have to wait the other times I jumped so maybe that means the battery is really dead. Anyway the problem is resolved (I hope.) Thanks.