Hi Alex, it’s a bit hard to triangulate from the information you have provided. For a start, an Egg serial number looks like the word “egg” followed by 16 characters [0-9] + [a-f]. Generally the first three are “008”.
If you use the Egg Serial Configurator desktop application and do some action with it (like set wifi) it will tell you the serial number whether it succeeds or fails. You can download that program from airqualityegg.com/setup.
A basic serial terminal program can tell you the same thing using 11500 baud 8n1 settings. If that doesn’t mean anything to you, forget I said it 
.