Factory resetting the V1000H simply resets all settings and options back to default.
It doesn't revert the firmware. Once your firmware has been upgraded, you can't downgrade back.
What you can do is use a root password and see if the .57 firmware lets you log in (as a recent patch disabled the root logins, but you can still try and see if it works), and then use a custom firmware (from this forum) to downgrade back to 48.
Telus forum users, please correct me if I'm wrong.