I was trying to find a draw on my batterie.I disconnected the positive side and put a ampmeter between the positive terminal and positive cable to read the draw.I then unplugged one fuse at the time to see if I could find the draw.I never did,but now ,the central locking system and alarm are not working anymore.I cant even open the trunk electronically.I rechecked all the fuses,and they all are good.What could be the problem????

 

that is a tricky one. I have seen BPM's fail and SLCM's fail. I have also seen trunk microswitches fail.
Go over the entire system to ensure a proper diagnosis.

 

Personally, I would have removed the negative clamp from the battery as opposed to the positive when checking for current draw. In any event, try disconnecting the negative clamp from the battery, leave it disconnected for about 20 minutes and then reconnect the negative clamp.

 

You might get a better response by posting in the X300 forum, which is the one for your car.