I have actually come across this before, where the error showed and the scene was empty, and all I did was go into another scene and open the broken scene using the SceneManager.loadscene function in a script while playing in a working scene. After that, it loaded and was fixed, although i dont know if that always works, or if it was really the same error, you probably messed around with it too much for it too work anymore but why not give it a shot.