The upgrade included in the A:1.04 / B:1.02 firmware for the Nikon D4 D-SLR is the improvement for the subject tracking performance in AF-C (continuous-servo autofocus) mode with framing using the viewfinder.The focus accuracy when using lens or teleconverter combined with a maximum aperture of F/8 was improved within the previous version.
These two updates result in a 51 strategically placed autofocus points, which, when used, along with the 16.2 MP, captures the clearest and highest quality pictures. All this technology is concentrated on the most rugged body that Nikon has created yet, which promises to protect against moisture, dust and electromagnetic interference.
So, if you want to update the camera's firmware, you must know that the process cannot be performed if the [Network] → [Network Connection] in the setup menu is ON. But, most important, make sure you use an EH-6 AC Adapter with EP-6 Power connector or a fully charged EN-EL18 battery.
This said, to do this right, in a way that would not result in the need of service work, take note of the above mentioned recommendations and follow the link suitable for your OS from below:
Nikon D4 D-SLR Digital Camera Firmware for Windows
Nikon D4 D-SLR Digital Camera Firmware for MAC