Assisting hatch--help!

[lilstar]

This hatch has been a MESS. Without getting into the drama (search my old posts if you wanna hear the story) I'm assisting the last surviving duckling. It definitely needs help, its back is totally glued to the membrane. I had been helping it slowly, picking away shell and membrane where I can. Its mostly out, but I stopped because I saw on its belly.. I'm not sure exactly what I saw. The "belly button" looked slightly open. I don't think I saw any yolk sac but it looks like it needs to close up. When I saw that I wrapped it in a paper towel, put it in a cup, put the cup inside a little bucket under a heat lamp. As far as I can tell, its doing fine. When I was working on its shell it was trying really hard to get out! Nice and active. Resting now, occasionally preening. Looking pretty good. So do I just wait a few hours then peek at the belly? I have no concept of how fragile this is, or if I'd hurt it by continuing to assist.