BMW F15 Xdrive35i broken all of a sudden

[F15_SGM]

Hi, I am needing some input on my vehicle. So I was driving and randomly car went into limp and drivetrain malfunction was on idrive. I lost all power rpm just acted like in neutral. I barley made it to an edge of the road. Restarted car and I couldn't get it into drive or reverse. Now I searched the form and found two scenarios that were similar to mine. So far I replaced both batteries with similar one's since battery tester said to replace. After that there was no change. The code my car pulls up is 421342. Do I really need a new transmission? It's just crazy because I kept my car well maintained and it drove like new. I had no symptoms of a failure like this beforehand. Aswell as I always believed the most reliable thing on this car was the zf8. One weird thing is my car was at the dealership 2 weeks before for out of warranty extended repair on a nvlp fuel related thing. The car really let me down this time and out of nowhere. I got the car into drive and reverse if I pull the gear lever as soon as I start the car. You can't wait after starting otherwise it locks it out. New battery was a 92ah Duracell and aux battery is a 520cca Ln1agm battery instead of the oem 570cca. Cost for OEM aren't justified for something that may not work

Those are the two Similar posts. https://f30.bimmerpost.com/forums/sh....php?t=1690459
https://f10.5post.com/forums/showthread.php?p=26318609