I'm sorry the chick didn't make it, but you did the right thing. One thing, though. Never, never do a float test on an egg that you think might have a live chick in it. That's a great way to kill the chick. Candling is a much better way to see if the chick inside is still alive.
Leave it alone. It's not uncommon for up to 24 hours to pass between pip and zip. If it's still having problems after that, it's up to you whether or not to assist, but be aware that if it's having problems hatching, there's likely something wrong with the chick and it may very well die...