You could try to wrap it in a wet paper towel, wet the towel with hot water, if you are worried about it being stuck. Just wrap the whole egg leaving tha pip and any fractured areas exposed and put back in the bator.
To me it looks like it is still absorbing, and just resting. The towel will keep membrane from drying while it rests, and then when ready, it will zip. I have had more than a few do this over time and the warm wet towel keeps the humid enough to finish absorbing.
If it looks or sounds stressed, assist slowly and carefully, stop at any sign of blood. Follow Sally's instructions and you will be good.
As for the earlier one that always lies down, my last assist did the same for three or four days, then I noticed it was much chubbier than all of its hatch mates. Took it a few days to develop the leg strength to walk around properly, but she is fine now.
