P3006 and won't start

Hello everyone. I just purchased a 2002 Prius from a government auction. The car had to be jump started at the auction yard. It ran for awhile and then died before I could put it on the dolly. I jumped it again, load it and towed it home. When I got home I jumped it and drove it off. I tried to charge the 12V battery on a 2 amp current, but it wouldn't charge so I replaced it with a new battery. Now the car won't start at all. Don't worry, I did not reverse polarity at anytime. Here's what is happening now:

1. It never does reach a Ready state. Instead, the screen turns on and shows the Main Battery warning and sometimes the one to the right of it that looks like a car with an exclamation point through it.
2. I plugged a cheap code reader into it and it gave me two codes: P3006 and P3006 P.
3. I cleared the codes with the reader and the screen immediately says Problem Solved, but then the Main Battery warning comes up again.
4. I took the back seat out to access the terminals to the HV battery. I checked these with a multi-meter both with the key off and then on. They read 0V. The meter is working because it reads the 12V voltage fine.
5. I checked resistance on all of the fuses in the three compartments under the hood and to left of the steering wheel and they all seem fine, so I don't think any of the fuses are blown.
6. The orange colored safety shutoff thing on the back driver's side of the HV pack seem to be properly installed.

Here are my questions:
1. Are the two leads on the drivers side front of the HV battery both positive or is one negative?
2. Should there be voltage at these terminals and, if so, what should it be?
3. Is there a fuse or relay inside the HV battery that is supposed to turn voltage on from the HV pack when the key is turned on?
4. If one of the cells goes completely bad inside the pack will it cause an open circuit that would cause the pack to read 0V?
5. Is it correct to assume that if the Prius computer senses something wrong with the voltage supplied by the HV battery that it won't even try to fire the gas engine?

Thank you so much for any help. This is actually a present for my dad that I'm hoping to give him on Father's day so it would be great to be able to diagnose and fix it by then.