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If pushing the override button didn't work then your problem is an internal problem in the shifter. This override will allow you to move the shifter without pressing the brake, so that rules out the brake/shifter interlock.
What happens is a plastic linkage piece for the ignition/shifter interlock cable breaks. When this happens the shifter won't move because it doesn't know you have the key turned forward. The fix is to remove the center console and replace the shifter assembly. This isn't a major repair. It takes less than an hour to do, and if your car is out of warranty and you have to pay for the repair, the replacement shifter assembly is only $42.
If your dealer does mobile service and will come out to repair it there, that may be an option. Otherwise you could have it towed to a dealer.
If you have some tools you may be able to get the shifter to move. If you pop off the chrome trim ring around the shifter and look down the gap left by the ring on the left side, down low you will see a pink plastic lever. Look down there with a flashlight, firmly hold the brake since the car will be able to roll (setting the parking brake would be the best idea), take a long screwdriver and pry this pink lever to the rear. At the same time with the other hand you can move the shifter back out of park. If you bring it back to neutral then you can then start the car, the shifter will be able to go into reverse and drive. As soon as you put it back in park though, you will have to go through the process of prying the pink lever again. Keep in mind by doing this you are overriding the safety feature of not being able to move the shifter when the key is out - if the shift lever isn't in park the car will be able to roll at any time.