Every time it tries to stand up on it's on? have you been able to get it to take some sips of water. The save a chick should help to give it some strength. I am going to be honest with you there is always a chance something else is going on too. Right now we can only wait. Keep it as stable as you can try not to stress it any by trying to get it to do things it can't yet, Hopefully like everyone has said now it is just time and hopefully by tomorrow you'll see a big difference in them.
It's also very important you clean the last one to hatch's umbilicus they are at a real risk for infection when they hatch like this.