How sad!
I had much the same experience with my
Brinsea Mini Advance. The first two hatches were 100%. Then 15%, then 0% and 0%. The eggs felt very warm and moisture was pooling under the egg tray. Very frustrating. I bought a second hand incubator (
Brinsea Octagon Advance Ex). So happy and optimistic - my 38th birthday present (that is the great thing about getting older!).
Then - bang! - disappointment again! The new incubator temp was off, according to the seller. Lots of stress with 6 different thermometers, all reading different temps - and 30 eggs waiting without proper storage.
Long story short: My small
Brinsea was 4 degrees off from the displayed temp, my new
Brinsea was 0,5 degrees off (celsius). I was cooking eggs in the small incubator, and freezing eggs in the large one.
I am now on day 10 with both incubators, correct temperature and mostly dry incubating them, hoping for top results now.
So, you should definitely get an accurate thermometer and hygrometer, and double check the settings before you start a new batch. Don't trust the display... Buying a new incubator does not always solve the problem!
Best of luck with the new bator!