Won't go into drive, hybrid system issue

Hey, so I've looked here before for answers but this is my first time posting. So I have a 2007 and the other day the big red caution light came on while I was moving my car to a different spot at my house. When I went to move it back it wouldn't go into drive or reverse. I saw others on the forum suggest charging the back 12V battery, so I did that. Everything seemed normal again, and I drove around a bit to see how things were, and the caution came back on. When I turned the car off and back on it went back to not shifting. I charged the battery again and this same result happened. I assume maybe there's an issue with the battery like a bad cell or something? The thing is, the battery is only about 4 years old and all the other functions it powers work, so I feel like the battery shouldn't bad that quickly. My car is higher mileage though, around 226,000 miles.

 

Thank you for the link, I'll look into getting a scan tool. To answer your question yes I did disconnect the 12V battery while charging. I also realized earlier based off of another thread I found that the charging wasn't what allowed the car to function properly for a bit, it was just the act of disconnecting and reconnecting the cables. I have a feeling the code will be the P0AA6 based off the other thread I found similar issues. I'll get a scanner to confirm