When the car is off, the brake lights will work, that's normal. Check the brake switch bracket to make certain it's not bent/broken. On the early 3G Optima's there was a problem and if I remember correctly the pad that the brake pedal contacts wears and the pedal is too close to the switch so it stays on. So the battery doesn't run down, you can take something and place it between the pad and pedal to get the pedal higher and see if the lights remain off. If they remain on, you can disconnect the negative terminal, but that will erase all the saved data.
Keep us posted.
I checked it and everything is correct, rather I think it is a short circuit or something like that because sometimes it is working normally and suddenly the lights turn on by themselves when the car is off in the garage as if I were pressing the pedal. It is strange, I have never heard anything like it. Any ideas about that?