Did you checked the Firewire cable inside the printer? It connects data relay card (installed in the PCI slot of the computer motherboard) with carriage board (in the carriage). If not, get a new cable (Firewire, 9 pins), switch off the printer, unplug original cable and plug yours routed outside igus chain. Then switch on the printer. It's even possible to print with FW cable outside igus, but you have to be very careful and hold the cable in your hands to prevent it from damage (gantry and carriage are moving...).
Also - have you checked LED diodes on the carriage board? There should be one blinking. What is the frequency of blinking?
Also - have you checked LED diodes on the carriage board? There should be one blinking. What is the frequency of blinking?