Get one of these and you should be set.
Yes I checked it, there was nothing in the replacing the battery section beyond a noticeI don't think there is any socket that is "on" when the "key" is not in ACC position...so I am not sure it will back flow the 9V into the vehicle...Did you check the owners manual to see what it said about the battery?
Well first thing I have to say is that an AGM battery is good, if properly cared for, for 6 years plus, to have replaced 2 in 4 years (2014 model and a 2018 post) suggests an issue beyond a battery. Not too mention that would have been covered under warranty so why would you change it yourself?I have replaced mine twice myself with no issues in my 2014. Disconnect the old one, remove, put the new one in and reconnect. You will need to cycle all 4 windows fully up/down is about the only thing I noticed needs to be done after you reconnect the new unit. I did not do this the first time and the rears refused to go down, had to disconnect/reconnect and cycle them to get them working correctly again.