Need help for resetting password on Surface Pro 2

Friend has asked me to reset password on Surface Pro 2, they haven't used it for a month and could not remember last password they used. Built-in resetting option won't work because it will erase all user files they have on that tablet.
I usually use Nordahl password recovery tool when i need to blank or change forgotten password, it worked fine for me on regular non-tablet Windows machines, both options - CD and USB boot.
I'm not familiar with Surface tablet, so i did online research on how to boot Surface from USB, tried all options, but was not able to boot it from USB stick (i used 3 different USB 2.0 sticks).
Here is what i tried:
I was able to get into boot screen and disable Secure Boot Control, then able to get into Advanced Options screen, checked USB drive option. Tried 3 different USB sticks with 3 different password recovery software - no luck.
Have anyone an experience with Surface Pro 2 password recovery? Either i'm doing something wrong, missing a step, or maybe older USB sticks don't agree with Surface USB 3.0 port? Should i try to plug in external DVD drive and attempt to boot from it?
Any help will be appreciated?

http://www.eightforums.com/general-support/53-forum-rules-please-read.html

6) No discussions of hacking someones system, network, password, etc.

You may have a legitimate reason to do this but forum rules restrict anyone from helping you, sorry.