Flashing Lumia 640 Missing Reset Protection Key


In a simpler term, this step is to change an ATT-phone as a genetic one, so we can flash the firmware from other carriers.

3.1 Install USB Driver

Move in side LumiaFlashTools>>Driver folder, and install the driver inside. When plugging the USB cable, the Windows took awhile to complete (~3-5 minutes)

3.2 Put Phone into Flash/Recovery Mode

Press and hold Power button until the phone vibrates (to restart) then press and hold the Volume + button untill you see a flash on the screen. The phone is now on the flash mode.

Flash mode
Lumia is in flash mode
3.4 Debranding Lumia Phone

This is the critical step to flash other Lumia firmware to the ATT-branded Lumia phone.

  1. Extract Lumia Cabs (Resource #6, step 2) into D:\Nokia
  2. Run cmd.exe tool with 'Run as Administrator' and move to D: driver (or where you placed the software)
  3. Run iutool to put the .cabs file into the phone iutool.exe -p -V D:\Nokia
  4. To check if the Lumia Phone is listed with command: iutool.exe -l
Flash mode
To check the connected device.