Before You Begin:

Either of the above-mentioned firmware flashing processes can cause data loss. Hence, we highly recommend backing up all your data, including photos, messages, contacts, and app settings, before proceeding with it. If you choose to proceed with flashing, on the OnePlus 6T, all data will be erased and irretrievable.

In addition, make sure to download the correct and compatible firmware for the OnePlus 6T from a reputable source. Use of the wrong version of firmware may cause malfunction of the device or your device might stop working. Verify that the firmware is for your OnePlus 6T with the exact model number before moving on.

Finally, make sure your device has enough battery for the flashing process to be completed uninterrupted. The recommended battery life is at least 50% to prevent the risk of power failure during flashing which can be critical and can lead to a severe condition like your phone being bricked.

How to Flash Firmware on OnePlus 6T

Download Necessary Files

• First, download the required firmware files of the OnePlus 6T (these may be available in a zip file with the MsmDownloadTool that needs to be used to flash the device).
• Download and install OnePlus USB drivers (Step is optional) These drivers will allow your device and computer to talk to each other, and, without them, the flashing process is not going to happen.

Extract Firmware Package

• Locate the compressed firmware package on your computer after the download is complete.
• Unzip the firmware package and place it on your desktop or somewhere easily reachable since you will be using this during your flash.
• Install MsmDownloadTool
• Then go to the folder where the firmware package is located, and find the MsmDownloadTool executable file.

How to Boot OnePlus 6T to EDL Mode (Emergency Download)

• First, turn off your OnePlus 6T.
• Plug the device into your computer via a USB cable.
• Now, press and hold the Volume Up and Volume Down buttons at the same time.
• Hold down both buttons, alongside the Power button. Continue to press all three buttons until your OnePlus 6T boots into EDL Mode (Emergency Download Mode).
  (If EDL mode does not automatically activate on the first try simply repeat the process or check the USB cable and port for a proper connection.)

Open MsmDownloadTool and load the firmware.

• Go to the MsmDownloadTool folder on your PC
• The MsmDownloadTool .exe file, right-click and select Run as Administrator.
• Next, once the tool opens, find the Target button and click on it.
• Go to the folder in which you extracted the firmware files and select all firmware files related to OnePlus 6T, The tool will now load the firmware for flashing.

Start the Flashing Process

• Select Start in MsmDownloadTool Step 1 This will initiate the flashing process for your OnePlus 6T firmware.
• You will now begin flashing. You will see a progress indicator in the tool showing the progress of the firmware installation.
• While flashing please do not unplug your device or use it in the middle. At this stage, any disruption can cause critical errors or even brick your device permanently.

Wait for Completion

• Flashing itself may take a few minutes to complete. Wait and let the process complete without obstruction.
• Don’t unplug your OnePlus 6T at this point.
• After successful flashing, the process will show a Success message in MsmDownloadTool.

Reboot and Complete Setup

• After cross-flashing, your OnePlus 6T, in many cases, automatically reboots. If that doesn’t work, force restart the device by pressing and holding the Power button until the OnePlus logo shows up on the screen.
• note it can take a bit of time for the first boot after flashing, as it optimizes the system and finalizes settings.
• After your device boots up, complete the initial setup process as requested.

Important Notes Must Share Before Flashing:

1. Make Data Copy: Flash firmware will wipe all of your data. Before running it, make sure to have backed up your files.
2. Applicable Applications: Using the wrong firmware can cause device failure or permanent damage. Always get the right version from the official OnePlus source.
3. Identify the Risks: FAQ: Flashing firmware corruptly can damage your warranty, and hijack and brick your device.
4. Also, Ensure that the battery has a minimum 50% charge before you proceed with the flashing process to rule out the power cut while flashing comes up.
5. Install OnePlus 6T USB Drivers: Without installing the appropriate USB drivers, your device may not get detected properly on your Computer.
6. No Disconnecting: When you flash with your device open MsmDownloadTool, do not disconnect or kill its process.

Final Considerations

Note: These instructions are general instructions to Flash the firmware on the OnePlus 6T; however, some steps may vary depending on the firmware version and for the OnePlus updates. Please always check official OnePlus resources and updated community guides before proceeding with the above workaround.

As long as you read this guide carefully and complete the flashing properly, you should now have your OnePlus 6T firmware successfully flashed and returned to a fresh, factory state. In case of any bottlenecks, do check with OnePlus support or ask experienced users in the community forums.