Help extract hdr for Dell Optiplex 9020M

[hp300]

Hi, Im currently using this machine and I need its BIOS file to be able to do some mods on it. I have acquired the original BIOS file from dell (exe) but I cant extract the BIOS file, tried /writehdrfile and /writeromfile but it doesnt work. So can anyone extract this for me? Thank you very much.
BIOS file: http://www.dell.com/support/home/vn/en/v...egoryId=BI