Are you using thew right flash program? I see you use a usb floppy but are you using Crisisdisk? Try this it worked on my board which is simalar to mine. Follow directions.
download this:
h30499.www3.hp.com/hpeb/attachments/hpeb/bsc-274/161072/1/354948.zip
follow instructions in this:
h30499.www3.hp.com/hpeb/attachments/hpeb/bsc-274/161079/1/355037.pdf