How To Flash HTC Desire Dual Sim 820U Firmware

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

fastboot flash zip firmware.zip

Wait too finished

fastboot reboot