Clio mk3 2006 possible immobiliser problem?

[ast]

Hi there, my close friend asked me to take a look at hes car, he says its not starting. Ive had a look but i cant figure it out! All the central locking has stopped working, doors have locked and i could only open the passenger door via the lock. When i put the key in the ignition and turn, the immobiliser light starts flashing rapidly and the car just wont turn over. Just seems dead although all the inside electrics work fine. Is this an immobiliser fault? If so what can I do about it? New ecu and transponder?
Also is there any way to check if its immobiliser?

I will appreciate the help, if anyone can help me! Thanks!

 

[ast]

Also, if he bought an ecu kit from the same year car, buy with a different engine size would it work?

 

[Sean6545]

Check for water inside the UPC under the bonnet.