I am so sorry this is happening to you.
The problem may not be with your technique or the bator, but with the shipping. If they got x- rays in transit then nothing will hatch. (That's my understanding anyway.) And with the post office holiday rush and the freezing weather, that might have also contributed to your hatch problems...
This was a new incubator to you right? I've noticed that both of mine have their own set of "issues" I didn't see coming. It took me several days to figure them out. And multiple posts on the forums...and multiple PM's...
My still air has temp spikes and drops and my
Brinsea, has temperature that is astoundingly even, but the humidity has taken me a while to figure out. (My problem, not the incubator)
I just started hatching so I think the next time I will do some local eggs and see if I can get a better hatch rate myself. (I got 5 hatches
total out of 2 dozen eggs (each dozen from a different shipped source) and one died. (So really 4 out of 24.)
If you have a source of fertile eggs I say Go for it! Then you will be able to rule out the eggs, which is a good start.
And better luck with your next hatch.
It is really worth trying again.