Td5 immobilised after battery change

Hi I have recently changed the battery on my Td5 disco and it seems to have immobilised its self key fob doesn’t work anymore and the physical key unlock doors but alarm goes off when doors open key won’t start it either you can hear the fuel pump but it won’t crank I’ve also tried to input the eka code which I got from main dealer but it wont let me start the input sequence there’s not beep or change to red light on dash when holding the key in the unlock pos not to sure what to do with it other than sending ecu off to get immobiliser removed any help would be appreciated thanks

So your vehicle the alarm set and in an immobilised state, so the dash LED is flashing while the vehicle is locked?

Unlocking with the key therefore activating the alam sounder is normal as the security alarm system is voltage sensing, you will always need a functioning fob to unlock, so assume u use the fob and it functions normally so is to check to why the fob isn’t working, so is it possible that the battery is flat, the LED isn’t illuminating when pressing the button.

I take it you don't have a spare functioning fob

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Had the fob tested and it works charged the battery also just incase

Also yes dash led flashes flashes, only have the one key for it unfortunately it also work fine previously

Don't see why changing the car battry should cause this problem. Try using your key as close to the sensor as possible. Located in roof linning just in front of rear sunroof. Can you get your hands on a spare receiver to try that. No programming needed- plug and play.
Griff