Well, you can candle and water candle if there are no pips. Other than that it's a matter of how long you want to wait. My very first hatch I had 17 going into lockdown. I had a faulty thermometer and didn't know it so my bator was running colder, a lot colder, than it should . I ended up with one hatcher day 24 and one day 25. The day 25 died leaving me with one surviving chick. It can happen.
Chances of them living if they can't pip themselves are slight. You can give them another day or you can mark the air cell where the internal pip is and pip into the air cell by the beak to see if you can assess the situation. Just keep in mind, the chance of survival if you have to pip into the air cell is slim and you can not second guess your decision. No matter what you do after it's done if it doesn't work out you are going to question if it wouldn't have been better to do the opposite. You have to do what you think is best and if it doesn't work, chalk it up to nature or you'll drive yourself crazy.
