i have a bmw e36 with possible immobilizer fault can u help?

i have a 1995 325 bmw, it has a single button seperate alarm remote supplied by bmw, first the central locking stopped working with the remote but still worked with the key, to start vehicle i had to put key in ignition and press button on remote which would turn off immobilizer and the car would start, i have changed batterys in key fob and the cars battery is only a month old.
the car will now not start and the led on centre consel is not flashing but is on key fob.
i have tried turning ignition to position one turning key back and pressing button on remote but still will not start or turn over.
can any one help
many thanks
Lionel