Reuse IronPort C160 as PE850 (replace bios)

Hey folks,

im trying to reuse our old PE850 based cisco ironport c160 (email security appliance) as a linux server for some internal monitoring applications.

as mentioned in the title i've been facing issues replacing the cisco ironport bios with the dell bios.

i downloaded the file PE850-A04.EXE and copied it to a freedos bootable usb. flash util can be started using command "PE850~1.EXE /FORCETYPE". flash util message "verifying system configuration. checking rom file. CRC-32 File is correct" appears along with the question: Press Y to replace "!!!" with "A04" BIOS.

after entering Y the screen stucks immediately. i've waited aprox 10 minutes (i've never saw an bios update taking more than 1 minute). if i press anything else then Y a proper message appears saying that the update was cancelled by user..  so it looks like the flash util works fine, only after confirm with Y everythings stops..

did i forget something?

The USB Stick has something around 15gb and is connected to the PE850 over an usb-hub alongside with my keyboard (since it seems to be the only possibillity to use an bootable-usb and keyboard at the same time).

i tried downloading the A01 instead of A04 but i cant use that program in dos..

any hints are well appreciated!