Fire protection mess ... was a symptom.
The root cause was that the local governments (city of Berlin and state of Brandenburg) wanted to split the pie for many small to medium businesses in the region. Noble idea but hard to execute as we found out later...
So instead of giving it all to a contractor that actually knows how to build (large) airports they tried to managed it themself. Those people were unexperienced in this size of operation and it went all downhill from there.
It's a common theme with big projects: Local administration is unexperienced but tries to do it anyway and they fail or get ripped off every time. What we should have is a federal unit that just does large scale construction/engineering projects.
Choose taste, choose the original!