iPhone 12 got overvoltage, is it repairable?

Hello! If an iPhone 12 gets overvoltage, what could happen to it's components? Not my phone, but they said that they wanted to charge it from a car radio, which turned out to be faulty, since then the phone doesn't react to anything. Is the motherboard saveable? I have an almost whole iPhone 12 for a donor if needed, apart from the motherboard and the screen. I'm okay with some easier microsoldering too, just want to know if it could be repaired, or it's a dead horse.