Let me take a shot at this.
You plug it in, get green, no, yellow... (pop) then nothing. Right?
I discovered my adaptor's flip-up plug wasn't quite touching the internal contacts and was arcing. (popping sound and ozone, too!) So, I used the power cord extention and swapped it for the flip-up plug. (I don't remember if the cord came w/ the adaptor or my Airport Express, but it works!)
Photo of said cord
Good luck
- David