Welcome to BYC! Great job trying to save them. Do you have or can you get any thermometers? Like a meat thermometer, a small digital thermometer, a mercury thermometer, etc. to test the temp with? You'll have to calibrate it, but that's pretty easy. What kind of incubator is it? To check how old they are, you'll have to candle them. Take a bright flashlight (even a phone flashlight will work) and shine it in through the fat end (the air cell end) of the egg. Like this.
View attachment 2222875
The above pic is how you candle. What you're seeing in the pic is an internal pip, one of the first stages of hatching. They usually hatch about 48 hours after the internal pip. This is a chart you can compare your eggs to. It will help you age them.
View attachment 2222881 View attachment 2222882
Also, if you can get some pics similar to the ones above I can help you guess their age. Look for nice veining and movement. If they're clear, or no veins, they're probably dead. Pics will help though. That should get you started. Good luck, and great job again for taking in those little darlings!