The controller is potted as a "hockey puck"; the electronics inside are not intended to be accessible for repair.
If you want to take it out anyway, see this thread:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=86600
for what things look like inside. I dont' have any info on how the system works, however, or what you might need to do for any repairs.
You could have an overheating issue causing either the controller itself to shutdown and cease communicating with the display, or just a cable with a wire fault inside it (anywhere between display PCB and controller PCB).
A wire fault is more likely. You could test the cables for continuity and connectivity if the failure is continuous; if it's intermittent it's much harder to find such a fault; you can only operate it and "wiggle" wires to see if you can either cause the fault, or to make it go away if it is already present.
To get the controller out, you have to take the other side of the rotor off, to get to these screws:
this post has pics of the controller with some of the potting removed (but you can damage parts trying to get the potting off)
https://endless-sphere.com/forums/viewtopic.php?f=2&t=86600#p1463159