That is the source of the problem then, the download was likely damaged or interrupted which caused the update to become corrupted.
Even though these units are capable of connecting to wifi for streaming, etc, it is never a good idea to update the firmware via wifi, as a failed install can actually cause permanent damage to the receiver.
Initially, lets try a microprocessor reset: Power off, then press and hold the ZONE 2 SOURCE / M-DAX buttons on the front panel, and keep holding them while powering back on, until you see the display flash, then release and test for functionality.
If no change, we can try a deeper factory reset process, and failing that it would need to go in to marantz factory service to have the control board replaced.
If these steps return functionality to normal, do not try the update again. You should only update by plugging it in to a wired ethernet connection.