> the car has an anti-theft device that was triggered by the installation of seats. There is a remote system to override the anti-theft device, but that doesn't work because it requires mobile reception.

I’ve been following the thread on Reddit and there’s an added piece you’re missing. The mechanic triggered the anti-theft device so the car went into an initial lock down, that can be disabled remotely by Ferrari. The mechanic contacts Ferrari who can’t override the anti-theft because the car is without signal. At this stage the anti-theft mechanism is also attempting to contact Ferrari, probably with location data to help recover the car, still thinking it has been stolen. But due to the fact that it can’t get a signal out, it assumes the worst and enters full lock down mode that requires some sort of fix that can only be performed by Ferrari themselves.