I hatch quite a bit, and had one like that in my last batch - I've come to believe that if they're not at least internally pipped within the +/- 3 day timeframe, there's usually something wrong that will prevent them from surviving hatch. The one in my hatch was 3 days past hatching day and by the time I "liberated" it (carefully!), it was gasping its last breaths.
Knowing what I know now, would I have just let it die in shell? Nope. I help with the hope - each time - that it makes the critical difference. And it has, at times.
Kudos for trying. It seems that it just wasn't meant to be.
