Other files can be on the USB drive.
Take it step by step and watch the PROG LED.
(1). Power the board on without the USB drive. THe PROG LED will blink briefly at power up and the board should boot to DONE. DONE indicates that the boot process is completed.
(2) insert the USB drive. PROG should blink once on mounting the drive and go out. If PROG keeps blinking at this stage there is a problem with the USB drive. You'll need to reformat the drive with MS-FAT32 or purchase a new drive. MS-FAT32 is the formatting used for new drives.
(3) Press and hold the left button. PROG will blink slowly 5x and then go solid for the installation. When installation is complete the PROG LED will turn off. IF PROG starts repeatedly blinking here there is a problem with the filename.
If the filename looks correct and doesn't contain any additional characters you may have a hidden double extension (chroma.rom.rom). You can try deleting the visible extension. Turn the power off and on again and repeat the process.