Good compa, I am watching in the self -body that your car has immobilizer, I ask ... the key with which you give the start is the original? It may be that if it is not it will not start or by chance. The only one that occurs to me if they give you the signs well is that you have a problem with the immobilizer. Sometimes the plastic that is behind the key itself is broken, and people boot it. This piece of plastic contains the transponder that sends the signal to the starter drum, if it is not attached to the key, the vehicle does not start.