If all you have is a blue key, you are in the brown stuff. The easiest way to check whether your car is coded or not is if when you switch on to accessories, is there a yellow light in the shape of a key with the word code under it, if there is you have an immobiliser, if not you are fine. Most Puntos had key transponder immobilisers fitted and when the car was new, you would be supplied with a blue key and a red key, the red key is the master which contains all the coding and information, it is also the one you get copies cut from, the blue key you have is only intended as a spare.you have two options, try and rip out all of the immobiliser stuff (if its fitted) or you will need to get a matched set of ECU, red key and crank angle sensor (yes this is coded too!), best place to try is your local breakers yard, forget FIAT, they are useless and pricey, I have an Alfa Romeo and I face the same problem with FIAT dealers, this is what happens when smart ass ideas get old, the flaws come racing to the surface and create problems.