# OnePlus 6T (fajita) **Warning! This process will delete all the data on the phone and may render the phone unusable. Please proceed only if you are comfortable with doing this. Basic android knowledge required.** **We're not responsible for bricked devices, dead SD cards, thermonuclear war, or you crashing into a tree because RetrOS crashed.** **YOU are choosing to make these modifications.** 1. **Prerequisites** 1. Download and extract [ADB and Fastboot (Platform Tools)](https://developer.android.com/studio/releases/platform-tools#downloads) onto your computer 2. Download this specific TWRP .img file and move it into the Platform tools folder (with adb.exe in it) ([link](https://dl.twrp.me/fajita/twrp-3.3.0-0-fajita.img.html)) 3. Download corresponding TWRP installer ([link](https://dl.twrp.me/fajita/twrp-installer-3.3.0-0-fajita.zip.html)) 4. Download and extract OxygenOS 9.0.16 Repack (MSMdownloadtool included) ([link](https://androidfilehost.com/?fid=6006931924117936340)) 5. Download the latest version of RetrOS for your device ([link as of 2022-07-13](https://drive.google.com/file/d/1Q2fapW2zI6hcS5Z2Jinox4h3wwFLctfV/view?usp=sharing)) 2. **Downgrading stock Android to 9 using MSMdownloadtool** *(requires a Windows PC, will lock the bootloader)* 1. Install Qualcomm USB drivers ([64-bit](https://www.mediafire.com/file/5wc5nk5adevatrj/QDLoader_HS-USB_Driver_64bit_Setup.exe/file))([32-bit](https://www.mediafire.com/file/q1uynnim8arbim9/QDLoader_HS-USB_Driver_32bit_Setup.exe/file)) 2. [Disable driver signature enforcement](https://windowsreport.com/driver-signature-enforcement-windows-10/#1) (shift-restart method) 3. Open `MsmDownloadTool V4.0.exe` you downloaded and extracted in step 1.4 4. Connect the phone to the computer using a USB cable (Stock OnePlus red/white cable recommended) if you haven't already 5. While the phone is off, hold all three (Power, Vol-up, Vol-down) buttons simultaneously until you see it pop up in device manager as `Qualcomm HS-USB QDLoader 9008`. 6. If you're getting N/A device in MSMdownloadtool, try using another USB cable 7. Once MSMdownloadtool says *Connected*, hit Start button 8. **Debugging:** virtually every error that results in an unsuccessful flash is caused by wrong USB cable/port. We recommend using the stock OnePlus red/white USB cable and a USB 2.0 port. If you're still having issues, try another computer before asking for support. 3. **Enabling USB Debugging (ADB)** 1. **Complete the Android setup** 2. On the phone, go into **Settings > About phone** 3. **Tap on Build number 7 times**. This will enable Developer options 4. Go back to **Settings > Developer options** 5. **Enable USB debugging** 4. **Unlocking bootloader** 1. On the phone, go into **Settings > Developer options** 2. Enable **OEM Unlocking** 3. Back on your PC, **open command prompt** in the Platform tools folder (with adb.exe in it) (on Windows, type cmd into the path address bar) 4. In CMD, enter `adb devices` to initialize ADB 5. In CMD, enter `adb reboot bootloader`, your phone should reboot and it should say *Fastboot mode* on its screen. 6. On the phone, an authorization pop-up may appear - if it does, authorize your computer 7. Once the device is in fastboot mode, verify your PC finds it by typing `fastboot devices` in CMD 8. In CMD, type `fastboot oem unlock` to unlock the bootloader 9. On the phone, a warning about unlocking the bootloader will pop up. Select `UNLOCK THE BOOTLOADER` using volume keys and confirm it with the power button 10. If the device doesn’t automatically reboot, reboot it. It should now be unlocked (can be seen by the warning that pops up at boot). The device will now reset completely. 5. **Installing TWRP** 1. Once the phone boots, **restart it**. While it's restarting, **hold the Vol-down button**. You should now see a black screen with a OnePlus logo and a selection of three languages (If you don't, repeat the process holding the button down for the entire duration of the reset). 2. You're now in the stock recovery - make your selections with volume buttons and confirm with power button. Select **English** > **Advanced** > **Reboot to fastboot** > **Reboot to fastboot** 3. Back on your PC, **open CMD/Terminal** in the Platform tools folder (with adb.exe in it) (on Windows, type cmd into the path address bar) 4. Once the device is in fastboot mode, verify your PC finds it by typing `fastboot devices` in CMD 5. Enter `fastboot flash boot twrp-3.3.0-0-fajita.img` 6. Enter `fastboot reboot` 7. The phone should reboot and boot into TWRP recovery 8. Once TWRP loads, copy the TWRP installer .zip you downloaded in step 1.4 from your computer to the internal storage of the phone 9. Back in TWRP, go to *Install,* select the correct .zip and swipe to flash 10. **Do not hit *****Reboot System***, instead go back to the main menu, hit *Reboot* menu and *Recovery,* while not installing the TWRP app 6. **Installing RetrOS** 1. Copy the RetrOS .zip file you downloaded in step 1.5 into the internal storage of the phone 2. Back in TWRP, go to *Install,* select the correct RetrOS .zip and swipe to flash 3. After installation, *Reboot System* while not installing the TWRP app 4. The phone will restart once by itself during installation --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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