Module HV battery chaos

I've read many posts, but can't seem to solve my battery issues (gen2 2004). Yes, I'm a newbie. Here goes...At exactly 200K miles all warning lights came on, including the red triangle. I drove it home (35 miles) thinking that maybe it was a 200K mile fluid change reminder or something. Had purchased it this summer and had already put 30K on it. Ordered an OB2 scanner and downloaded a couple of apps, including Dr. Prius. I had immediately gotten battery codes pointing to #4 module. There was a difference of 1.64 voltage with car running. Thinking I could change one module, I ordered two cells. Removed the battery and did a voltage test on all cells. #4 was way low, as were two other cells (#26 and #18). Ordered two more cells. In the meantime, removed the metal bus bars on one side of the battery where there was a lot of corrosion and cleaned them well. Took a dry brush and cleaned the posts. I did this up to cell #26. On the other side with all of the wiring, there was no corrosion on the bars and I was afraid to remove the harness, so dry brushed them for good measure. Removed all of the cells up to #26. Then put all of the cells back in and put the 3rd cell (#26) which I thought was faulty at position #1, as well as the companion cell and then companion cells to #4 and #18 (as i had replaced those bad cells). Put the battery back in and started. Used Dr. Prius and it showed that cell #1 was faulty, which I had suspected would be. The car wouldn't go into drive and I received the yellow triangle, along with the red triangle, etc. (Realized later that I hadn't fully engaged the safety block (didn't push down). Replaced cell #1 and the next one as soon as the new cells came. Started right up and ready light. Drove it around the yard a bit and took it for a drive. Didn't read any codes, until exactly 2 miles up the road. Ran the codes and got C1241, C1377, U00773, and U0293, plus Dr. Prius showed #28 and #14 as bad. Reset 12v and ran it two miles and this time got P3019 and P3000. It also seemed to lose power and limp along. Reset 12v and made it home 2 miles and all lights came on with P3019 and P3000. This morning reset and same two codes. Fan blows immediately.

No. I did not torque the 8mm on the bus bars. Made them snug and then a quarter turn (45 deg).
Could it be the ECU? How can I test this?
Can I check continuity to make sure it's not the wiring harness? And how.

I am thinking maybe it's time to just get a new battery, but I hate to throw in the towel, although it's our only vehicle and we need it quickly. (And my husband is getting tired of lugging that battery in and out of the house) I am worried that if I put money into a new battery, it will end up being the ECU or some other component. It just doesn't make sense to me that I am playing whack a mole with modules.

Sorry if I gave too many details, but I thought it might help in finding a solution. Would really appreciate some knowledge as mine, which was limited to begin with, is zapped.

 

I would hate to invest in a new battery and it still not run because it’s the ecu. Do you know a way to test it?