That should be the only file you need
When I go to update my LiteOn LVW-5045, I have a file with the same extension, write it to a CD-RW (with verification), put the disc in the LiteOn and within a minute up comes a message asking if I want to update the firmware.
When you burn the file, make sure ‘CD-ROM (ISO)’ is chosen and just in case it is an issue with the ISO settings, match them up with my screenshot below. When you begin the burn process, make sure ‘Verify written data’ is chosen. Alternatively, if Nero still gives issues, use the Windows disc writing system to write the disc as it will create a compliant disc. To do this, right-click on the file, click ‘Send To’ and select your CD/DVD recorder from the list. Click the balloon that that appears on the bottom of the screen and then click ‘Write these files to CD’. The default volume name should be fine. Finally follow the on-screen wizard.
When you place the written disc in the DVD Recorder, give it at least a minute to recognise it as I have seen my DVD Recorder take over a minute one time to recognise the firmware update disc.