Anything else I should check before replacing the HV battery?

The dash on my 2008 prius with 120k miles lit up like a Christmas tree a couple of days ago with the big red triangle, VSC, check engine and the brake system warning light. The little car outline with the exclamation point in the touch screen too. I got the codes read and they were C1241, C1310 and P0A80. I reviewed threads/posts and got the ideas to check the "12v" auxiliary battery and the HV battery cooling fan. At idle with the back hatch open the 12v battery read 12.4 volts, which I understand might be a little weak (a 12v battery actually starts out closer to 13.2v, I'm told and less than 12.6v indicates it is getting old). It was an Optima battery and it was 3.5 years old and I'm in Texas so I was guessing it was time to replace it one way or the other. I got a new Optima battery from Amazon for $145+tax delivered. It is 12.8v right now, btw. I installed it and it started up and no lights. The gas engine came on and I could see that the HV battery was registering one bar but it pretty quickly charged up to 4 or 5 bars and went green. I started off in a hopeful mood, but a hundred yards later the same set of lights came on. I took the cooling fan shroud off (at this point most of the back of the car is pretty torn apart). The cooling fan looks good and by hand is spins freely, but it didn't come on at any point. I went home, turned the car off, and let it sit for a few minutes and then started it again. Once again it starts with no lights, and the HV battery shows one bar and starts charging. Questions:
1. Should the HV battery cooling fan have turned on? If so, how to troubleshoot it further.
2. Is this behavior indicative for sure of an HV battery failure? or should I risk a visit to the stealership to make sure?
3. In Texas is the warranty on the HV battery 8 yrs/100k miles or 10 yrs/150k miles?
4. Has anyone installed one of the Dorman replacement batteries with the 3 yr warranty and had either really bad or really good luck? I can get one at Advance Auto for $1400. The one from Toyota is almost twice as much with the same 3 yr warranty, it appears to me.
I can split this into several different posts if needed.

 

The car only ran for 5 minutes so maybe the HV battery didn't have time to heat up enough for the fan to come on. I have the plastic shroud off of the fan temporarily so I can see the actual fan blower and normally I could hear it even if the shroud was on. I can get a Dorman for $1400 from Advance Auto.

 

A friend at Advance Auto loaned me his personal code reader - an Actron.

 

For reading standard OBD2 codes you don't have to use a Toyota brand scan tool. For deep level manipulation of actuators etc yes, you have to have a dealer level scan tool.

 

So, I called Toyota, they assigned me a case number and said I first had to take it to a dealer to get checked out. I went to the dealer today and they wanted $4000 to replace the battery. I mentioned I was a member of PriusChat and that I had hoped for some sort of goodwill discount. The service consultant offered $500 off at that point and suggested that I talk to Toyota directly if I wanted to try to get them to do something. I called 800-331-4331 and they told me that I was out of warranty and said "What are you requesting". I said I was hoping for a goodwill discount since I was the original owner and I knew that in CA the warranty is 10 years and 150k miles. He asked me to wait and then came back and said they could offer a $1500 rebate - after I paid the dealer send i the paperwork and they would send me a check in 3-4 weeks. In the meantime the service consultant talked to his boss and he offered an additional smaller discount. So, net-net, after I get the rebate it will cost about $1800. Thanks to the folks here who suggested calling Toyota and asking for a goodwill discount. You saved me over $2000! and I get a genuine OEM battery replacement. Oh, and I got a free loaner car for the day too. I really appreciate the people who come on here and out of the goodness of their heart try to help other people.