Depending on how far the control box is from the valve box, you could try one of two things. A, check continuity from each zone at the controller to the solenoid. It almost sounds like the bundle of wires you found in the yard has a short somewhere so when one zone activates at the controller, it's shorting to the zone you see always activate. Rhe other thing you could try is running a long loom of new wire from the controller above ground to the solenoids and temporarily rewire them direct so that it bypasses that loom in the ground. If that fixes the issue, you know that bundle of wires is the culprit. If it's easier you could bring all of the solenoids to the controller and wire them there to see if each commands on like they should, and again this would point to a wiring issue with that bundle.