Peugeot 406 immobiliser light on

Had water on drivers footwell, dried it out and the multi plug under carpet, now the keep unlocks the doors and indicators flash but display states economy mode and ignition on ok but immobiliser light is on and can't start car.

Tried disconnecting battery, and ignition on with key button pressed still no joy light will not go out and car won't start, checked immobiliser fuse all ok just cannot start due to immobiliser.

Any help would be appreciated on how this fault can be fixed....