Sounds like a PATS(passive anti theft system) problem...turn your key on then off quickly 10 times in a row, (on the 8th time you should hear your automatic door locks engage) and then after the 10th time it should start.
I had same issue. The anti-theft thinks you are stealing the car. Sometimes it will crank but only if the light is flashing at a regular pace but if it is too fast then it will not turn over. Have a mechanic put a new ignition harness on it.