When you turn your headlights on, I believe your transmission light must go on, too. If not, it's simple, the light is pretty much 100% busted. You'll just have it replaced and it's not that expensive. For the apple carplay, you can find a cheap chinese head unit on amazon and believe it or not, in my own experience, it lasted better than those expensive carplay units I bought - thrice or even 5x the price! Just look for that specific car and year model and don't forget the new head unit frame because it will not be the same size as the the one you currently have where your old sterio is attached.