When i try to start the car it wont turnover an it keeps blinking security on the dashboard

If you have the second ignition key's with you try it.  If not try this, it takes about 30 min to do. 30-Minute Learn Procedure 1. Turn ON the ignition, with the engine OFF. 2. Attempt to start the engine, then release the key to ON; the vehicle will not start. 3. Observe the SECURITY tell tale light. After approximately 10 minutes, the light will turn OFF. 4. Turn OFF the ignition switch, and wait 5 seconds. 5. Repeat steps 1 through 4 - two more times - for a total of 3 cycles of 10 minutes. 3x10 = 30 minutes. The vehicle is now ready to relearn the Passlock Sensor Data Code and/or passwords on the next ignition switch turn from OFF to CRANK Important: Turn the Ignition Switch OFF. The vehicle learns the Passlock Sensor Data Code and/or password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle. 6. Start the engine. The vehicle has now learned the Passlock Sensor Data Code and/or password. 7. With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles. Without a scan tool you may have momentary starter interruptions while history clears itself. Good luck and hope this helps, keep me posted, be glad to help

Your key has a computer chip in it that tells the computer that the person who owns the car is trying to start it. Sometimes the key will lose its memory and the car computer thinks your a thief with the wrong key. You may have to have a new key made from a code the dealer can aquire from the VIN number I believe.