Making good "underground" electrical connections is key. Silicone filled "grease caps" wire nuts seem to work best.
Some valves are a piloted valve, meaning there's a small electrically actuated valve which controls the "pilot". Once the pilot is opened, the water pressure opens some sort of a piston or spool which opens the main flow path. Some valves, Hunter as I recall, have a quarter-turn screw thread on the pilot, so you can manually open the valve to check or diagnose or irrigate, all without the benefit of electricity. However, left unscrewed too far, the valve will leak water and not be in control of the pilot flow.