Onkyo A-9000R DAC CM6631 firmware

I bought second hand this amplifier. The only issue was playback from pc through usb port. The amp was seen by pc as mass storage device.
I found out that previous owner flashed wrong firmware to this DAC. I found flash tool from c-media and their firmware 2203. The input is working now, but I would like to bring it to original state.
Onkyo official doesn't want to share their on board firmware, so I'am asking you guys for help.