Okay, got the test code working and I now have the controller code working (with some spare conductive fabric and some crocodile clip cables. I guess I need to unpick the old model and redo the stitching to see if that gets it working, in the meantime would changing the code to play a note simply be along the lines of changing the code so instead of "pressing" A/B/Start/Select etc, it plays NoteC5, B5, etc? I will look into doing this in the meantime, I know I need to include pitches.h and there are different commands I will have to try and learn.
I've definitely proved that the circuit needs work, it's probably just the stitch I've used. I am hoping that it's going to be a simple edit like instead of connecting the pins to key presses they just play a note.