 This application will remove Windows 10 from the device and restore the most current Windows Phone 8.1 software and the device's latest available firmware (i.e.Lumia Cyan or Lumia Denim).Microsoft issued an update to the Windows Phone Recovery Tool in April 2015 to address difficulties for Nokia Lumia 520 and other low-memory devices while installing the Windows 10 technical preview, because their limited (512 MB) memory caused these devices to become "bricked".