That's just fear mongering nonsense from the dealer. If you had the tuner device that should have been given to you then it would return the vehicle to the factory tune whenever you want. Actually, every time you would put a new tune on it the device would return the factory program to the PCM. It's a standard practice and assuming that the dealer does things by the book it won't do anything to the PCM.I recently bought a 2017 mustang gt and it had a mystery tune didn’t find out about it until I went to get new tunes, the tuning company told me I’d need to reflash it back to stock for them to make the new tunes so I took it to a ford dealership and they told me that reflashing could lock my pcm and told me if it did it would be 900 to replace it. Any suggestions on what to do because I wasn’t sure if they were just feeding me bull do I have to spend that just too get new tunes?
If they try to tell you that the car's PCM locked up then I would demand to watch them reload it again and try to start the car as I would suspect that to be an instant bs story. I'm pretty sure that the dealers make you sign a waiver as standard practice but there's nothing to worry about imo. I don't think that I've ever heard of such a thing happening.