>> A friend with a recent X5 had to surf YouTube to find out how to log into his car's firmware to tell it that he was changing the battery.
That's the least of it. What happens when you do reconnect a battery to an "intelligent" car can be mind-boggling. Better to connect a small 12-volt battery across the terminals to maintain enough trickle current to keep the autodroid alive while swapping the big one. You can bodge something together with torch batteries if need be.