On this page, you will find the official link to download HTC Desire 620G Stock Firmware ROM (flash file) on your Computer. Firmware comes in a zip package, which contains Flash File, Flash Tool, USB Driver and How-to Flash Manual.
How to Flash
Step 1: Download and extract the HTC Desire 620G stock firmware package on your computer.
Step 2: After extracting the package, you will be able to get the Firmware File, Flash Tool, Driver and How-to Flash Guide.
Step 3: Install the provided USB Driver on your Computer, and if in case USB Driver is already installed, SKIP this step).
Step 4: Follow the How-to Flash Manual to Flash the Firmware on your HTC Desire 620G Flash File Device.
Take a Backup: If you are going to flash the above Firmware on your HTC Desire 620G Flash File device, then take a backup of everything as because your personal data will be deleted after flashing the stock firmware.
The firmware shared on this page is officially released by the company and helps you to recovery your device if you ever got bootloop, software error, update error, hanging and dead issue.