Stepper controller not working

I have had a Routout CNC machine for a couple of years but after laying idle over the winter it is not working.
I have considered this to be a 'plug and play' device and have no knowledge of the detailed workings but have acquired enough skills to operate the machine.
I have some knowledge of electronics and expect I could repair the stepper controller if I could identify the fault but I don't know how to.

If anyone can point me in the wright direction I would be most grateful.

Thank you John