On My Omnia PRO B7610 with 6.1 ROM (Asia/India), hardreset works by this procedure :

1. Press and hold Work & Life button and Lock button simualtaneously.
2. Press the reset button while holding the above two buttons.
3. When the Samsung logo appears, simualtaneously press send and end keys while still keeping the first two keys pressed.
4. A message will appear to confirm reset, press yes and you are done!

I hope it helps