Yes, I chose to replace the 12 V battery myself after watching numerous videos on YouTube, and reading of others on their process here on this site. I purchased the Remy. I watched multiple videos to make sure that the process was pretty well uniform across all the videos, just trying to be cautious in case someone “accidentally “ left out an important step, e.g., if they forgot to mention to disconnect the high voltage battery. You don’t want to skip that step.
To bless/authorize the battery, I also purchased the Foxwell device. I think I have read that others may have skipped this step in process, but I can’t be sure about what their results were. I did not try to use Bimmercode to authorize the new battery.
I wrote all the steps down to keep me organized since I had not done this before. I went so far as to place a cover over the bay so as not to lose an errant screw or bolt. A screw still fell down there, twice. I am now the proud owner of pliers with a magnet taped to it. Luckily, I was able to retrieve what I dropped into the bowels of the bay.
I checked with the dealer first to see what they would charge to replace the battery when the oddities appeared. They are 60 miles away. My vague recollection was that they wanted somewhere near $500. It was a wash for me, as a new battery and the Foxwell device was just shy of that number. But I reason that I now I have a Foxwell device if I need to run a diagnostics on the auto. Also I had no idea if the car would actually make it to the dealer or if it would cut out on me halfway.
So your experience may vary, and I can say I hope I don’t have to do this again too soon. At least I know how to do it now.