car immobilizer and central locking problem?

hi
i have 2000 model hyundai elantra with immobilizer and central locking. one morning i tried to open the car window with remote and it didnt open. i opened the window with key and then tried to turn on the immobilizer and it didnt start but did so on third or fourth attempt. then everything worked fine the whole day.

next day same happened and the ignition was never turned on. i changed the remote batteries too but no response.
now when i open the car window with key, the hazard lights start flashing and a LED also flashes continiously.
but cant turn on the immobilizer with the remote. so cant drive the car now. everything else (power windows, stereo etc works)
even checked the fuses, no result. please someone help me