I had a duck egg that I thought was dead so long story short took the top of the shell off..... What I did (others helped me) was put coconut oil on the membrane, this was done around every 8 hrs to keep it moist), then cover the hole with plastic wrap. And bumped up the humidity a bit to help...
Tue May 7 was day 21 so while it was overdue it was only a day over which can happen especially if there is cool spots in the incubator. is the baby still alive today?