Once your in the directory of the flasher the command you should use for flashing the image is...

flasher-3.5.exe -F RX-51_2009SE_1.2009.42-11_PR_COMBINED_MR0_ARM.bin -f -R

Turn off your 900 and input the command in the flasher then at that point press u on the keyboard of your 900 and flasher will detect the device and start to flash.

Let me know what happens.

copy and paste ok.