How to: Flash leaked Windows 10 Mobile ROM’s on a Windows Phone device

Windows 10 Mobile


Yesterday we have reported that on a Chinese website Windows 10 Mobile ROM’s have been leaked and it was even possible to download them. To be more precise, the ROM’s which have been leaked was the Windows 10 Mobile Insider Preview Build 10240 and it was available to download them for the Nokia Lumia 930, the Microsoft Lumia 640 and the Lumia 640 XL. It is quite hard to understand anything at all at a Chinese website, (obviously, it’s more complicated than any computer science assignment), however if you came that far and you have downloaded the right ROM for your device there is still the problem how you can get the ROM file flashed on your device. The answer to this question is the Windows Phone Image Designer.


The Windows Phone Image Designer was made especially for this reason, of course Microsoft has not made this to flash leaked Windows 10 Mobile ROM’s, however now we can use this tool to get the job done because Khaagan over at the xda-developers forum has modified the Windows Phone Image Designer tool so that it can be also used with unofficial ROM’s.
Of course there is always a bit of a risk doing this and I am not responsible if you brick your phone while flashing Windows 10 Mobile Build 10240 on it. I have tried this already with my Lumia 930 and it is working just fine and that is why I am posting this tutorial here, however that doesn’t mean that there can not occur any problems on your device.
According to the description Microsoft has on its Hardware Dev Center for this tool you can do the following things with it:

  • Create a new Windows Phone image.
  • Modify a Windows Phone image that was previously created using Phone Image Designer.
  • Customize the phone image according to your desired user experience, or to meet network or market requirements.
  • Define runtime configurations for your image based on the SIM inserted in the phone.
  • Build and flash the image to your phone.

“Phone Image Designer makes it easy for you to create and flash a customized Windows Phone image. Phone Image Designer also provides error logging to help aid error detection and provides basic image-level validation against the feature manifest.”


So if you have decided to try flashing this leaked Windows 10 Mobile Insider Preview Build on your Lumia 640 / XL or Lumia 930 you can follow the steps below to do this. Be sure to fully charge your device before you are doing this because this process does use a lot of battery on your device and if it goes off during flashing it will make your phone useless.

  1. BackUp:
    First of all you have of course to a fully back up of your device. Best method to do that is probably to connect your phone via USB to your PC and just copy all folders on the phone to your PC so that you can copy them on your device afterwards. You might also do some screenshots of all the apps you have currently installed because loading a backup is not recommended on Windows 10 Mobile yet. It makes you phone buggy and less stable.

  2. Windows Phone Image Designer Download:
    The Windows Phone Image Designer is a Tool developed by Microsoft which makes it possible to flash ROM’s, .ffu files, on your Windows Phone. This would of course be also very helpful to flash custom ROM’s however i is not yet possible to create custom Windows Phone ROM’s. Anyway we need this tool do flash the leaked ROM and you can download it from Mega via this link. You can also download the original LumiaFlashTools archive which has been uploaded by Khaagan and which does also include the drivers for your device, you can ignore the NaviFirm+ program which is also included in the archive tough since this is useless for what we want to do here.

  3. Microsoft FFU Download Mode:
    Next step is to bring your phone into FFU Download Mode in order to be able to flash your phone with the downloaded .ffu file. Therefor you have to switch off your phone once you have done this hold the Power and the Volume up button. When you phone vibrates release the Power button but keep holding the Volume up button until a small gear and a flash are displayed on the screen of your phone. Now you are in Microsoft FFU Download Mode and you can connect your phone to the PC.

  4. Windows Phone Image Designer:
    Once you have prepared your phone and downloaded the Windows Phone Image Designer you are ready to start off, extract the downloaded .zip file and go into the folder which has been extracted. There you have to double click on the Start.bat to open the tool. Now it should look something like in the screenshot below. To continue to the next step choose “Flash a Windows Phone image onto your phone” and click on “Next”.


  5. Choose Phone and ROM:
    Last but not least you have to choose which .ffu file should be flashed on your phone what you can do by clicking on change and selecting the downloaded ROM. You do also have to select your phone in the drop down menu. The device name should have MSM in its name along with some other letter and numbers.


  6. Start Flashing:
    Made a BackUp? Phone fully charged? Sure you want to do this? Okay, so now you can click on flash and wait. It will take about 5 minutes until flashing is finished but be sure to wait until the Windows Phone Image Designer says that flashing has been ended successfully. Once flashing has finished your phone will reboot automatically.


  7. Congratulations!
    Once the flashing process is done the Windows Phone Image Designer Tool will say something like “Congratulations! Your device has been successfully flashed with the image you have selected.” and afterwards your phone will automatically restart.



So that’s it, really not that difficult isn’t it? However you have to carefully follow the steps mentioned below otherwise it could brick your phone. As already mentioned I am not responsible for any damage which occurs on your phone. Currently it is also unknown if it will be possible to directly upgrade to the next Windows 10 Mobile Build which is going ot be released by Microsoft so it might happen that you have to return to Windows Phone 8.1 so that you can install the latest Windows 10 Mobile Insider Preview Build once it has been released by Microsoft.
The only Tool needed for this process is the Windows Phone Image Designer and a ROM as you might have realized. The Windows Phones Phone Image Designer is an official program from Microsoft which allows ypu to flash ROM’s on a device. This does also mean that Microsoft does have detailed instructions at the Hardware Dev Center. If you want to get a more close look on the Windows Phone Image Designer you can head over to the Hardware Dev Center in order to see what else is possible with this powerful tool.


Feel free to drop me some questions about this flashing progress below. In case you are expereincing any problems I will try to help you solving it. If you have not downloaded the ROM files yet, you can do so by having a look at the links below.

Nokia Lumia 930

      • – Password: 8axc

Nokia Lumia 640

      • – Password: uf52

Nokia Lumia 640 XL

    • Password: fvji


Stay tuned for more information about upcoming news of Windows 10 Mobile and new Windows 10 Mobile Insider Preview Builds. Be sure to check back in the upcoming days as we will publish a hands on article with Build 10240 and a hands on video.

Source: Khaagan – XDA-Developers