Gradall xl3100

Hey guys im new here and trying to find some info on a gradall I cant find much info on them online The issue im having is that I cant start the machine from the upper cab Whenever I try to crank it nothing happens except the Orange Engine Malfunction comes on. But if you keep shutting it off and trying it again, itll eventually work. It usually takes about 15 minutes of trying. Now the schematics show the whole circuit is tied into another circuit and it just keeps cycling around. We have changed relays, switches and even changed the processor. Now when you turn the key on, in the upper cab only the let PTO light comes on Any help or suggestions would be greatly appreciated