From everything I've read on the forums here, this is what I've gathered:
-Day 23 isn't necessarily a bad sign. It just means that your incubator temp may have been a little low which lengthened your incubation period a day or two.
-From the moment the chick internally pips (breaks the inner membrane) it can take another 24 hours for hatch to complete. Sometimes a little longer.
-Someone mentioned once that they've heard of people letting hatches go on for 35 days and still get a healthy chick at the end. I, personally, am capping my hatch at day 25. Whatever doesn't hatch by then is gone. (That means I've got another 9 days to go.)
Where you able to tell why the one chick died? Knowing the cause of death of the first chick may answer some other questions.