I agree with lemurchaser. That's a long time to go without finishing zipping. And I have had it go both ways--I've had a baby die in the middle of zipping, and I've had them get stuck but survive after being helped.
HOWEVER: If the baby is dead, you can't do anything about it. If it's just stuck, it will be just fine waiting for the next time you open the incubator.
I DO NOT wait five days to open my incubator. I have found that leaving large numbers of babies in the incubator with hatching babies is more dangerous than opening the incubator every 12 hours or so to remove the fluffed up babies. Here's what I do: When I have five or six babies hatched, I add a bunch of hot water to the incubator through a tube, to get the humidity off the charts high. Then I quickly open, remove all the dry hatched babies into a container beside the incubator (any old box or basket will do), remove their empty shells into a trash container right by the incubator, and pull out any eggs I've decided need help. All this I do very quickly but carefully--don't get in a *rush* because you'll drop something. Close the incubator.
Put the babies in the brooder, throw the shells in the trash. Do whatever you're going to do to help the egg that needs it. Then repeat the humidity procedure (adding hot water, unless the incubator humidity is still way high, in which case don't repeat) and return the egg to its place.
For a baby that's mostly zipped when it needs help (and the only time this has happened for me is when other babies slept on *top* of a zipping egg all night and sealed it in), I won't even place it back in the incubator. Instead, I prepare (ahead of time) a small box with its own heat lamp and a soft covering on the bottom--basically a miniature incubator without the precise temp controls (it doesn't even have to have a cover--you'd be surprised how warm a box with a lamp over it can get). After helping the baby zip, I leave it in its shell and set it in the make-shift brooder/incubator. It will usually then finish hatching on its own. If it doesn't, I'll help it with the next step. And so on. I leave it in the separate brooder until it is coordinated (but not necessarily all the way dry) enough to fend for itself with the older babies in the main brooder.
Good luck. I hope the baby's okay, but if it's not, you probably couldn't have done anything anyway. Some babies just aren't ready for the world, and so they don't come out.
