The temp dropping, unless it was way down for a long time, should have only caused a little later hatch at worst.................
If you think about it.the hen gets off the nest to eat ect. and it does not hurt the eggs..........
Mine get off for quite awhile sometimes.
Of course , I don't know for sure.but I would guess the humidity may have caused shrink wrap.
There are just so many things that can go wrong that have nothing to do with us........
It does not take long for this to happen if they are on lockdown.
Goodness knows, I've done that one myself and been heart sick.
I know Rebel has much more experience than I do. Maybe he will check back in.
Do you have another incubator?
I have two...one for the first 18 days and the other for lockdown and hatching..............
Some folks make a hatcher.but I don't know how....
There is information here though............
By having the courage to write in with your problem.I think you did everything right.....
Good luck