[need flashing help] HP SFF 8300 troubleshooting bios flashing

[Vechs]

Hello, I think this is my first post, so here it goes :
I have modified my sff 8300 bios (from the stock, oldest version, v2.05) to include the chipset and 2nd advanced settings page. the problem at the moment is that i cannot flash it, it shows errors as :
DOSFLASH shows error -> System ROM image is invalid. (tried modifying a 2.51 to include the chipset and 2nd advanced menu method)
AFUDOS shows error -> BIOS has no flash information avaliable (/pbnc /n method)
Another error - > 46 - Error : Problem getting flash information. (/GAN method)
Another error -> BIOS does not support AFU (/P /B /N /C  /E /K /REBOOT method)
flashing it via just regular bios, shows the error
File is missing or damaged. (it is listed properly)
Any suggestions on this problem or is it write protected? (maybe getting a manual flash, like with a chip programmer?)
I can include the bios versions if needed. (on next post)