A picture would help to give better advice. But generally, I use coconut oil, paint it around the membrane closest to the shell and go inwards, but not where the beak broke through. What you are looking for is blood vessels to see if there is blood still moving through the membrane. If not then I generally will remove, GENTLY, a bit of the shell, always adding more oil as I go so the membrane becomes transparent so I can see what is going on.
That is taking into account the chick is not making swallowing motions with its beak, meaning it is still absorbing the yolk.
If the chick is not swallowing, and it looks more like the membrane has stuck somewhere, I will gently remove more shell, oiling as I go and if need be gently tearing the membrane until the chick can free itself. the last acts of the chick pushing its way out of the egg is what strengthens the legs and feet. More times than not if you completely de-shell a chick, you might be better served to put it in a small glass with some paper towel on the bottom before putting it back in the incubator so it can strengthen its leg's for a couple of hours depending on how weak it acts.
A lot of times, if you can free the head, and make sure enough oil is on the membrane, the chick will do the rest.
But like I said, a picture will help to give more than a general response and more directed to the situation your chick is going through now.