I had one do this to me last spring and it made it out. Just remember, don't rush to help. When they pip on the wrong end they have skipped the internal pip so they are way ahead of schedule on the others, like a day. Just keep the humidity up to keep membrane moist. Since you have other eggs in there, you at least have a "proper" timeline to guess at. Wait till the others pip and zip and that should give you an idea of when the veins and yolk are absorbed and it is ready to come out. If it doesn't start zipping after the others have, you may have to assist, but that is up to you. Good luck.