Hold down the up arrow button and boot the machine.  Hold it down until you see “firmware update wait”
Put the engine code to the printer using an FTP session. 


Update the engine code first.

Commands:
ftp xxx.xxx.xxx.xxx  <enter>
at user prompt, hit enter <enter>
at ftp prompt type in bin <enter>
type in put engine25.bin <enter>

When it is done, the control panel on the printer will ask you to reboot.
After it reboots, proceed to the controller firmware update.

Hold down the up arrow button and boot the machine.  Hold it down until you see “firmware update wait”
Put the system code to the printer using an FTP session

ftp xxx.xxx.xxx.xxx  <enter>
at user prompt, hit enter <enter>
at ftp prompt type in bin <enter>
type in put 7300122.prn <enter>

When it is done, the control panel on the printer will ask you to reboot.