Hi Jeff,
The first thing I’d do is to try to narrow the problem down to the valve and its wiring or the OpenSprinkler. The way I’d do that is to swap the wiring for the lawn valve to a different spot on the OpenSprinkler and then try to turn the lawn valve on and then the other valve that you swapped it with. If the problem follows the lawn valve, you might have a valve in need of replacement or a problem with the wiring to the lawn valve. If the problem stays with the lawn valve’s original spot on the OpenSprinkler, you might have a problem with the OpenSprinkler.
Mike