I help chicks all the time, the majorly important thing to remember is to let them pip and let them push themselves out of the egg- zipping is a fairly trivial in between step and in a lot of shipped eggs or eggs where the humidity has been to high, zipping is a near impossible task because the chicks may be too large to turn. Cracking away some of the shell for them has never hurt any chick I've helped. The other thing to keep in mind is that chicks can take upwards of 24 hours to hatch- 16 hours is not uncommon or even worrisome, imo. The chick is probably exhausted from pipping and what work its already done and it's perfectly fine for it to take long breaks and just sit there breathing. The way I usually tell whether it needs to sit or not is by the condition of the inner membrane. If it still has veins visible, the chick is NOT ready to hatch, helped or not. It is still absorbing blood and though you can't see it, is still absorbing the yolk. Once the membrane has lost the veins and become opaque, THEN the chick should be hatching on its own or may need help.