Hey thanks for your help, I actually have solved the problem via first installing raspbian then retropie following the video below after installing with NOObs and now I everything works as intended.

Still have no idea why the boot didn't work for me but at this point I am more interested in relaxing and playing some lovely 8bit games on my Picade. May be I can bump this later on when my curiosity kicks back in.

Have a great day.