sorry to say there is no remote way to control the valves unless they are already wired to a controler. rain bird does make battery powered timers for individual valves.

jt, Just seeing the error message with M says its with the pump relay may not make specific sense to most people but it would to a profession pump contractor who set these systems up. A pump electrician needs to check the system out from pump to controller hookup. The display is similar to the check engine light coming on in your car. The read out doesn't necessarily call out the exact problem and may actually disguise the real problem. That is why a contractor with experience with pump/controller issues needs to troubleshoot the situation. If your system was installed recently, you may be under warranty. You need someone who can troubleshoot the electronics. If you think you have the know how, DIY. GL JMHO Aloha

Hard to say as the link you provided to the photo is broken. You could try to attach it directly to your post.

it sounds like your most likely problem is a bad wire connection on the common wire. the best thing is to go to the valve boxes and recheck all the wire connections and redo them as needed.