Use a burning program (like ImgBurn or even Windows Media Player’s burn feature) to burn the ISO image to the CD-R. Select "Disc-at-once" and finalize the disc. Do not just drag the file onto the disc—it must be bootable.
Breathing New Life into a Classic: A Guide to the Pioneer BDP-51FD Firmware Update pioneer bdp-51fd firmware update
Download the BDP-51FD_V171.zip file. Extract it. You should see a file named something like BDP-51FD_V171.ISO or a .bin file. Use a burning program (like ImgBurn or even