OK, so at the moment, A12-J4 is NOT plugged in.  There is a red connector (fits) coming from backbox without a label.  Its the only red one...
So should they be connected together....(just cautious don't want to plug wrong shit in and really make a mess)

Yes it needs to be plugged in...however, site unseen I cannot comment on if thats the correct plug to plug it into...but if it fits it most likley is!