anti theft wrong key

There's something else going on here with the security system. I had a spare key made for my 08 Grand Marquis, a Ford Product, and it wouldn't start the engine until it was programmed to the vehicle. Trying to start the engine with that key had no effect on using the original key. You can't bypass the security system and yes you need 2 working keys to program additional keys yourself on a Ford Product. You need to be towed to your local Ford Dealer for repairs. Trying to fix it yourself without the proper equipment and knowledge will only make this worse and more expensive than it has to be! Jim

Did you try waiting 15mins before starting again. Put the good key into the ignition and turn to the ON position and wait for the light to go out, then crank it. If that doesn't work disconnect the negative battery cable off the battery for 15mins, to clear the system, reconnect and try the above.