The fact that the top panel has been broken off the device and the amount of dirt on it implies this machine will be requiring a service technician and not a simple reboot or update the firmware response.
My guess would be that the HDD is no longer in it.
What was the 2nd HDD, because if it can't find its OS on the first one and displays that message, and then you put an empty drive in it and it displays the same faulty, it truly implies the HDD is the issue
i have other xerox 4260 and it working without HDD.
i think that HDD is not reason.
i change motherboard and result was same.
i change display and reason was same.
now i dont know what can i do :(
Not booting up with message "Communication Error"