Well, I'm getting answers all over the place.
This is bonus, so no LCD. Yes, get GUI and can ssh. With or without cubes, same response. I hope its not the controller board. That may prove hard to replace.
The difference is I advocate correctly isolating the problem before throwing money at it if possible.
Based on your response I'd put the BBB last on the list of suspects.
It sounds like you already did all this but lets review.
Unplug everything and start with the simplest possible, just the controller.
Add one cube retest, try a different cube same ribbon cable.
Only change one thing at a time and see if anything works.
Test with the last known locally working version of firmware.
I'd completely unplug the whole controller from everything and let it sit unpowered for a many minutes. I had one I thought I killed. I replaced it with a spare Hoopiter controller. After few reflashes the original came back to life.
This may have been because I had everything unplugged in between flashes and whatever caused the 'lock up' cleared.
(some residual capacitance somewhere in the PCB design that affects the FPGA or the power chip on controller)
The reflashing I did may not have been necessary, the process may just have provided the long enough power down for it to clear.
My priority was getting it back in service so I never properly isolated root cause.
Another thing you can test for.
Take a single cube, unplug the cube power but connect the ribbon.
Turn on the controller and see if the temp on the ASIC shows up on the web page.
The temp chip on the cube is powered by the controller over the ribbon.
If this works the controller is prolly OK, as it tests controller power chip and FPGA operation.
This might/could point to a wierd 12VDC issue on a cube interfering with controller communication.
If/when you think throwing money at it is a good idea...
You might find a used Merc, Sat, or Jup controller with a BBB for what a new BBB would cost.
Those old knc specific BBB lack some connectors and might not be valued as highly seperately FWIW.
YMMV
Can someone make a diagnosis and tell me if my cubes are burned or my controller is burned ?
When i am running only the controller, the screen works and everything seems ok but
When i am connecting one cube the screen is not working any more, no green flash light , and less green lights on the controller