Always with natural incubation I leave them totally alone. I never help, if they don't get out of the shell there is a reason, and that reason is usually that they are just not strong enough. If they don't have that strength they don't do well after hatching either. The problem goes back to what is put into the egg by the parent stock, if the nutrition or health of those individuals is not prime the chick will be weak and do poorly. With natural incubation unless your broody is not dedicated to the plan you have no incubation issues.
With incubator incubation I learned quickly that it's also best to leave them alone. It's really hard to do but again the issue is far more likely to be that the chick is inherently weak. If you had big incubation condition fluxes your better off to resolve those than to try and work it out with this particular chick. It can be heartbreaking either way, I meticulously tracked chicks from a few of my early hatches that I had humidity issues on and had to help out. They run really high on joint deformities and foot problems and in the heavier breeds most often die young. True with some of heavies that is an issue, but these died even before they matured, far before I would expect for the breed problem. That and the joint and foot issues seen have convinced me that I just need to be better at hatching conditions and it has paid off for me.
Sorry for your lost chick but yes, just always leave them alone. Figure out the problem and correct it for the next hatch.
