Us the hatched chick in there with the pipped one? If not put it back in. I assist if it's longer than 24 hrs from the beginning of the external pip. But it's up to you. If you can see it's stuck in the membrane and it's been 36 hrs since external pip, it's probably not going to make it out alive, but you never know. There are two schools. Those who never assist and those who do. Those who do find sometimes they can help and get a success and sometimes they lose the chick anyway. If u do assist, go slow and free the head, moisten the stuck membrane, if it is stuck, with warm clean water. Stop if there's bleeding and staunch flow by pinching off vessel or dabbing with cornstarch. I wish you every success whichever path you choose. Plenty of YouTube vids on assisting some are good some are deplorable.