1. Download the ROM for your phone from the link above.
2.Download windows phone image designer from the link above.
3.Put your phone into UEFI mode by turning it off and then booting it while holding the VOLUME UP BUTTON. You should see a lighting bolt on your screen.
4.Plug your phone into your pc through Usb and open windows phone image designer. Select the x86 folder or the x64 folder depending on your version of windows.
5.Click on the Start.bat file and windows phone image designer will launch.
6.Once booted select "Flash a Windows Phone image onto your phone" and click next.
7. Your device should show up under flashable devices. Click on change and select the ROM you downloaded.
8. Hit "Flash" and wait for the program to finish flashing.
9. Once done your phone will reboot and you will have installed build 10240 on your device!
Sent from my Windows 10 using XDA Free mobile app
I got an error:
Sorry! Your device could not be flashed with the image you selected.
Please correct the following error and try again:
Failed to flash with device error { 0x16, 0x0, 0x0, 0x2, 0xa, 0x4 } : Image targeting check failed. Device: Nokia.MSM8926.P6204_ATT.1.1, Image: Nokia.MSM8926.P6204.
please help