Here are the instructions from Kenwood to setup a custom startup screen for the Kenwood DNX5120:
Please follow the steps below for loading/changing start-up screen.
· First connect the USB thumb drive containing image files.
· To enter setup mode. Press SRC+EJECT, then RESET.
· Select the OEM
· Select the file you want use.
· When the image is loaded, press Enter.
· Your new opening will remain for a few seconds and then switch to Source Select menu