In this we will show you how to unlock windows phone bootloader and then enable mass storage mode on your Lumia windows phone. This will work only for x2x devices that include Lumia 520, 620, 625, 810, 820, 822, 920, 925 and 1020. Mass storage mode on windows phone is not available as it uses MTP aka media transfer protocol instead for transfer of data to and from computer.
WPInternals: http://www.wpinternals.net/index.php/downloads (Download the latest one, 1.2)
WDRT: http://rightlaptop.com/uninstall-windows-phone-10-and-roll-back-to-wp-8-1.html (Needed for drivers)
HEX loaders: Link
1) Download and install Windows Device Recovery Tool (WDRT)
2) Download Windows Phone Internals (WPInternals) and extract that in a folder (for example C:\WPInternals)
3) Create a folder named “Loader” into C:\WPInternals
4) Download HEX loaders and extract it in the folder previously created.
5) Download SBL3 engineering archive (Only if you device is in supported list). Link
6) Create a folder named “SBL3” into C:\WPInternals and extract the SBL3 Engineering archive.
7) Download FFU image of your phone from WDRT or from lumiafirmware.com
* After entering flash mode you should do:
* The first one you need to select an FFU image
* If you downloaded it from WDRT, go to C:\ProgramData\Microsoft\Packages\Products\RM-xxx\ and select the ffu image file. WARNING: ProgramData is an hidden folder.
* The second one, select the folder “C:\WPInternals\Loader”
* The third one, if you device is supported, select your SBL3 Engineering image (In my case, Lumia 920) from the folder “C:\WPInternals\SBL3”.
* BEWARE that you can brick you phone if you flash the wrong image.
That is it, you have successfully unlocked your windows phone.