Before you begin:

• Back up your important data as the process might result in data loss.
• Download: Download the correct firmware for your OnePlus device from a trusted source. Ensure it matches your device’s model number.
• Make sure your device has sufficient battery to prevent any interruption during the flashing process. (at least 50%).

Flashing Firmware: 

1. Download Required Files:

   • Obtain the official firmware for your OnePlus 3. Ensure that the firmware is compatible with your device.
   • Download MsmDownloadTool, which is typically provided by OnePlus or can be found on official forums.

2. Install Necessary Drivers:

   • Install the OnePlus USB drivers on your computer to ensure a proper connection between your OnePlus 3 and the computer.

3. Enable USB Debugging:

   • On your OnePlus 3, go to “Settings” > “About phone” > tap on “Build number” multiple times until you unlock Developer options.
   • Go back to “Settings” > “Developer options” > enable “USB debugging.”

4. Boot into EDL Mode:

   • Turn off your OnePlus 3.
   • Hold the Volume Up and Power buttons simultaneously until the device enters Fastboot mode.
   • Connect your OnePlus 3 to your computer using a USB cable.

5. Run MsmDownloadTool:

   • Extract the MsmDownloadTool ZIP file that you downloaded.
   • Run MsmDownloadTool.exe as an administrator.

6. Load Firmware:

   • In the MsmDownloadTool, click on “Target” and select the firmware file you downloaded.
   • Click on “Start” to begin the flashing process.

7. Wait for Completion:

   • The tool will begin flashing the firmware. Wait for the process to complete. This may take some time.

8. Complete the Process:

   • Once the flashing process is complete, your OnePlus 3 should reboot automatically.

9. Disconnect and Check:

   • Disconnect your OnePlus 3 from the computer.
   • Check if your device is working properly with the new firmware.

Remember that these instructions are based on general steps for flashing OnePlus devices. The exact steps might vary slightly based on the specific firmware and version you’re using. So we can’t take responsibility for these instructions. Always refer to the official documentation and resources for your device and tools.