[OnePlus 8 Guides, News, & Discussion] badshah99:
Disclaimer

While I will assist with any issues resulting from this guide, I disclaim all responsibility and cannot be held accountable for any consequences caused by the use or misuse of this tool or process. This method also will wipe your phone, so please back up your data. I also will disclaim any understanding as to why exactly this works, since this method was developed by someone else, I am just listing the instructions on how to use it. With that being said, understand your personal limits and read this entire guide before starting.

Thanks to the attributed users at the end of this post, to find this method we are waiting for years...👍

METHOD 1:

Part 1: Requirements:

• To follow this guide you will need

A Windows PC

• Latest MsmDownloadTool for Oneplus IN2017 - Link

• Latest version of platform-tools - Link

• The bootloader unlock.ops file - Link

Plug your phone into your PC using a USB 2.0 port (this is important, USB 3.0 has given me a lot of issues and just doesn’t seem to work all the time) and ensure USB debugging is enabled.

Extract the downloaded platform-tools zip and open the platform-tools folder in a command prompt, and Run adb devices and makes sure your device appears in the list.

Next, extract the instantnoodlet_15_O.16_201001.zip and open up the MsmDownloadTool V4.0.exe inside the instantnoodlet_15_O.16_201001 folder.

When the application opens, select “Others” under the User type dropdown and hit next. Leave this window and the platform-tools command prompt open.

Part II: Entering Qualcomm EDL mode and installing correct QDLoader Driver

Part III: Flash Stock Firmware

In this section, we will flash the stock IN2017 Android 10 firmware.

Click the “Start” button in Msmtool. This will flash the stock firmware, wiping your data. Make sure you have backed your data up at this point. It will take a few minutes, usually ~300 seconds. Once it completes, it will reboot into factory default android 10.

Close MsmDownloadertool and once you are back to android, unplug your phone and power it off.

Part IV: Unlock the bootloader

In this section, we will flash the unlockable firmware and unlock the device for good.

1. Inside the directory with MsmDownloaderTool V4.0.exe, there should be a file called “instantnoodlet_15_O.16_201001.ops”. Remove it from the directory, either by deleting it or moving it to another folder. Then take the unlock.ops file downloaded earlier, and drag it into the directory and rename it to instantnoodlet_15_O.16_201001.ops . It should be in the same folder as MsmDownloaderTool.

2. Reopen MsmDownloaderTool V4.0.exe and like before, select “Others” in the drop down, and click next. Leave the window open.

3. Hold in the Volume up and down buttons, then plug your phone back in. Keep holding the buttons until your phone connects to your PC as "Qualcomm HS-USB QDLoader 9008", like before. Check device manager to ensure that it’s connected correctly as a COM port. If it boots to android, power it off and try again.

4. Return to MsmDownloaderTool. Make sure the phone is still displayed in the list under the associated COM Port.

5. Click start. The flashing should take about 15 seconds, and when complete, your phone should restart. It will display a message at boot saying “<!> The device is corrupt..” Do not panic, this is normal.

6. Unplug your phone and hold Volume Up, Volume Down and Power until the device reboots and let go once it shows the OnePlus Logo and “Fastboot Mode”. You should arrive at a screen that has “Start” in big green letters at the top, and “Fastboot mode” below it, with the very last item saying “Device state - Locked” in red text.

Plug your phone back into your computer.

7. Return to your command prompt window open in platform-tools, and run fastboot devices and ensure your device is in the list.

8. Finally, run the command "fastboot flashing unlock", it should prompt you to confirm unlocking the bootloader. Once complete, it should reboot into Android.

9. Shut the phone off again, and then Hold Volume Up, Volume Down, and Power and let go when the OnePlus logo and “Fastboot mode” shows up on screen. If the final item in the list says “Device State - Unlocked”, Congrats! You have successfully unlocked your bootloader. You can follow your custom OS’s installation guide from here.

If you want to flash back to stock firmware again (relock bootloader), you have to first flash this file (stock.ops) and then flash the bundled stock firmware. It will give a mismatch error if you do not.