Overheating n55 issues
So I bought a 2012 640i drove fine for 400 miles then the water pump went changed it drove fine for another 2/3k miles after that it started over heating as my water pump would turn off I noticed the battery voltage would stay around 15.6v I was told it's the alternator overcharging and threats what's making my water pump shut down to protect itself replaced that and the battery as it was extremely discharged it drove find for a weak then the same over heating my water pump would show as seen on the picture I read that is default values or a sign of a bad water pump I also as a los code so I replace the battery sensor.
So l assumed well maybe the bad alternator burnt out the water pump again so l exchanged it under warranty for a new one and installed it and got the same issue, I still have the code as see on picture for coolant pump missing, I noticed on bimmer link the pump will run for around 10-20 seconds showing
14. Something volts with 124rpm and same for the target speed then all of a sudden it'll go to 25.5v 205c for internal temp on water pump and 255rpm even tho the pump is not running as the car will overheat, I read that the ivm could've been damaged when my volts were too high from the old alternator so l replaced that and still the same issue. I've been trying to fix this for months now and I'm struggling with no working vehicle any help would really be appreciated