im not sure why its so far away from the backflow preventer…but I was 95% sure the sprinkler guy that came out a year or so ago showed me this box and told me it was odd that the master was in the back yard and it took him a bit to find it. I’d tested and that was the master for sure…something was wrong along the line. Luckily there were two additional wires running from the box to that yard box…I’m guessing for installation of the backyard zones when needed. There is already a pipe in that box ready for a valve…but only one…so I may be ok long term too. I was able to tone it out. I had 4 total additional red cables not in use and found the one needed…hooked it up…and the solenoid is now working as expected however along the way I have done something to prevent water flow as discussed. Figuring that out now. To be clear that zone does fire for each and every other zone…and was the one hooked into the master. Like I said it was working fine for like an hour…then just stopped. Now that I think about it it stops when the zone runs that would get the wiring running back to it wet. The problem lies there somewhere but I’m not finding it now or ever most likely if I don’t have to 
Thanks for the tip on finding the other zone boxes…that will be very very helpful…I can use a poker and trace the lines until it hits something!