In case this happens to anyone else... I accidentally set a cracked egg, and didn't realize it until candling on day four. I saw the cracks on the bottom as well as the developing embryo. I was really torn about throwing it out, but decided to seal it it up with melted birthday candle wax and check for growth/movement every few days. She (he?!) ended up hatching out into a perfect chick.
2nd from the bottom left
Hatching between the two chicks:
One with the darker yellow head on the left.
2nd from the bottom left
Hatching between the two chicks:
One with the darker yellow head on the left.