proper procedure to follow:

switch off your phone but don't plug in yet
open cmd.exe as administrator
cd c:\program files\nokia\flasher (assuming this is the path)
flasher -f -F main.bin --erase-user-data=secure
[plug in your phone that is powered off now]
flasher -f -F main.bin -F emmc.bin --flash-only=mmc


where main.bin is the rootfs file and emmc.bin is the emmc file

once done plug out your phone

follow this and report back...