[RUU] Desire Dual Sim KitKat 820U Stock FW 4.4 ASIA_INDIA
For product: a51_dtul
Firmware Download: here
Note: File download must not unpack
Install fastboot drivers from below if you have not previously installed ..
Note: If using Windows 8 / 8.1 / 10, be sure to disable the driver signature check before installing drivers.
Download tool fastboot unzip
Now put in the downloaded zip in the same folder “fastboot.exe” and rename it to “firmware.zip”
Open a command window in the current directory (Shift + Right Click on the folder and then select “Open Command Window here”)
Boot into fastboot mode (Vol down + Power then select fastboot)
Now type the following commands ..
Fastboot reboot-bootloader 1.
Fastboot oem lock 2. (If Bootloader Unlocked previously been if not ignored)
Fastboot oem 3. rebootRUU
Wait out logo HTC
3. fastboot flash zip firmware.zip
Wait too tringh finished
4. fastboot reboot