Step-1: Download stock official firmware for HTC One to the computer.
Step-2: Download Fastboot. Extract the files from the Fastboot zip ****
Step-3: Turn off the HTC One then reboot the device into bootloader mode. To do so press and hold Volume Up and Power buttons together
Step-4: Connect the HTC One to the computer using USB cable while it is in the bootloader mode *
Step-5: Open a Command Prompt window on the computer by pressing and holding the Shift button on the keyboard and right-click on any empty area on the screen, then select Open command window here ****
Step-6: Type the following command into the Command Prompt Window: *
fastboot oem rebootRUU
fastboot flash zip firmware.zip ***
Step-7: When the action is completed, reboot the phone
As the HTC One boots up successfully, it should be unrooted and running on stock official firmware.
Sent from my One V using xda app-developers app
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