I honestly think reports of frying the IBM (Intelligent Battery Monitor) are over stated.. let's put it this way - if 18V out of a dodgy alternator didn't fry the one in my last E64, 14.7V out of a charger isn't going to..
Oh - and Battery Registration just resets the learned charge profiles and stores the mileage of the battery replacement into the ECU
Which I'd do, if I could find the damned option in my tool (which is all in German
). It's more important to either replace the battery with the same capacity (which I did - 110Ah!) or make sure you re-code the vehicle option list to accommodate the new battery size if it's either lower or of a different type (swapping from AGM to lead acid or vice versa) as over-charging an AGM will kill it pronto.
I'm no stranger to NCSExpert etc
Anyhow .. all fixed.
I thumped the roof.
A lot.
Basically (which became obvious when I looked at the sensor readings), they are apparently prone to one of the hall effect sensors getting a bit "sticky" and then it thinks the roof isn't fully up - and when it thinks that, it will let you roll the windows
down but not up again. Which has the neat effect of making a slightly annoying fault (roof stuck up) a very annoying fault (windows stuck down)! FFS, BMW.
Anyway I literally just beat on the roof to rattle the sensor and now it's fine again - roof goes up & down normally. I just need to get in there now and clean & lubricate the slider on the sensor to make sure it doesn't get stuck again
Stupid cars...