Has anyone had an iinexperienced endodontist cause a root canal gone wrong?

Yes...: Unfortunately, every profession has its bad eggs, despite how many credentials on the wall. In fact, if there are too many, would worry about the self-confidence of the professional. Having said that, am not sure what you are basing your statement that the endodontist is 'inexperienced'. That is not an assessment you can likely make. Perhaps you are just pissed.

Of course: There is always the possibility of someone doing something wrong - malpractice vs a poor outcome to normal treatment.

Of course!: An endodontist has 2 or more additional years of formal training as compared to a general dentist. However, the additional training does not guarantee competence or perfection. In many cases a general dentist can do a root canal treatment that will be as good, if not better, than that of an endodontist. Also, keep in mind that even good and experienced clinicians have failures!