Changed rotors and pads on 06 525xi while pushing calipers back for new pads fluid overflowed from master cylinder onto the floor . After completion of the jjob I have no brake booster

Are you saying your brakes no longer work?

The booster isn't working . I have manual brakes only , no power. The pedal is rock hard , but the calipers are working.

Have you bled the brakes? That would be a good place to start.

Yes, even though no air entered the system .another thing is that after the brake and rotor change no brake service light appeared on the control panel. There is no fluid in the booster as I've read on bimmerfest .... I've done all the test to check booster for vacuum , and all tells me the booster is not working. So next step is test vacuum from pump , which I hope it's not the problem . It's very strange that the brake booster goes out after rotor and pad change .?????? Thanks to anyone that can help me with this problem

Also I've read that ceramic pads and new rotors can cause a hard break pedal , but it's like rock hard .