Can't go into D, nor R after replacing 12v

This is also posted in the Gen 2 forum, but I am nearing decision time and need any help I can get...thanks for your understanding.

First, thanks to all that post regularly within this discussion board. I have found great value by simply viewing many threads when problems arose with my 2005 Prius...however, I am in need of help, and my main counsel for cars is away without phone access, for too long...

I am by no means even slightly savvy about the ways of the Prius, but I have finally run into a problem that is perplexing enough to warrant seeking your help and telling my story about most recent troubles, directly.

Disclaimer: I went that route of a Green Bean replacement of the hybrid battery about 1.5 years ago, or so. Everything has been fine since the replacement, although I'll circle back to this later...also, the car has just over 193,000 miles on it.

The meat: after sitting for a week in Milwaukee, WI, I started my Prius and noticed right away that some warning lights were on, including the red triangle of death. Everything seemed okay at the time, and I was late to work. So off I went, cautiously. I made it.

Then, when I first tried leaving work, it didn't start. I did very basic research and determined that everything was symptomatic of a dead 12v. No problem.

Thus, I changed the 12v with my Pops/my main counsel for cars. I used an ACDelco, and the correct one. Everything seemed to be done and connected correctly. A note: there was a LOT of water in the trunk and battery compartment. I know that is fairly, "normal," but it was quite shocking...

In any case, the car started and went into drive after first attempt to start-up. Perfect. There were some warning lights that were still on, but it was late that night, so I opted to take a look at it later...I left, and the car drove fine and with no noticeable issues on the way home.

The next morning, I started the car, but it would not go into drive, or reverse. The car would only go into neutral and park. However, later within the day, at night, after attempting to put the car into drive and reverse again, it went into drive. I was thrilled. I then drove the car around for about 20 minutes and parked. I turned the car off and then tried to start it and put it into drive and reverse again...of course, I was unable to do so.

At this point, I checked this board and found nothing that seemed to lead me into the right direction, given my exact circumstances. I read a lot about issues pertaining to not being able to shift into drive or reverse, but nothing added-up. Perhaps I am bad at searching the boards for answers, which could be true. So I tried to get the car into drive again the next day, swearing to myself that I would bring it into the Toyota dealer for further investigation.

The next day, I was able to get the car into drive and got it to the dealer. I relayed the issues at-hand and they were immediately puzzled. Two days later, I was told that Techstream provided conflicting codes and that they essentially had to run an Electrical Diagnostics Test, of which would cost $304-ish. They also said that it is possible that I accidentally cleared the codes with a generic reader, of which is very possible, leading to the overall complication of the situation. But couldn't they just try and drive the car again, of which would ultimately generate more error codes? Regardless, I obliged to running further testing thinking it would *maybe* provide badly needed insights. However, it did not.

What I was told is this: they looked at my hybrid and said that there is, "battery acid everywhere" and that the hybrid needed to be replaced. Not a problem! I have a Green Bean, of which is still under warranty. Not bad news.

Then, the kicker: they told me that the EPS ECU needed to be replaced...what? I drove the car to the shop, and power steering was the last thing that seemed wrong...so confusing. In any case, Toyota stated that I need a new EPS ECU, of which with labor, and given that there is only, "1 left in the country," costs $1,395. Not only that, but I would not be charged for the 5 hours of labor, on top of the 3 they already provided for Electrical Diagnostics Test...I became skeptical, but what can I do?

Now, am I crazy or does an EPS ECU seem easy to obtain online for around $50? Why does it cost so much? Is it hard to replace? Is a lot of work/labor required? Is it worth buying an EPS ECU online and replacing myself and with help?

Overall, I just don't know what to do. Even if I replace the EPS ECU myself, and see that Green Bean replace my hybrid battery for free, will I continue to see issues? Toyota is not sure and confident that the care will be issue-free, EVEN IF the repairs they say need to made are completed. But it may be worth the risk if the EPS ECU is cheap. Also, and perhaps most importantly...am I missing something?!

Thanks for any help offered, in advance! I need to get the car out of the dealership, soon. If I can drive the Prius out of the dealership, great. If not, the plan is to either get rid of it, or tow it to my Dad's house to eventually work on it. But I don't know what route to take, yet; I am torn.