[OnePlus 8 Pro  Guides, News, & Discussion] Extreme_Ninja2099:
This is a bit late but why not. THIS IS A COMPILATION OF ALL THE OS METHODS YOU NEED FOR THE OP8 Pro.

ENJOY my guide :)

DISCLAIMER:

*I am not responsible for bricked devices, damage to your device*

Sorry for a long list of methods, some work for others and some don't. But I recommend to pick a method and stick to it. Maybe read the part at the top as some have notes about mine or someone else's experience/recommendation. Don't skip steps and follow each step.

If stuck, just ask and I or anyone else will try and help 🤗

I am here to post methods for anyone who is interested/need help. I have tested these myself and helped others who may be struggling :)

Download

The guide has loads of files/ zips/ tools to use/flash/install. But no worries as everything can be downloaded and there are links AT THE BOTTOM OF THIS THREAD (NOT COMMENTS) to where to download:

SDK Platform Tools (Fastboot tools) from Developer Android

TWRP from infected_

Magisk from topjohnwu

Gapps (Google Apps) from NikGapps. I recommend omni for ROMs that don't include Gapps.

Fastboot ROM for OP8Pro from mauronofrio

MSMDownload tools for OP*Pro from Some_Random_Username

IMPORTANT NOTES!

YOU REQUIRE Platform Tools (Fastboot Tools) IN ORDER TO USE THE METHODS IN THIS GUIDE AS TWRP NEEDS TO BE INSTALLED!

YOU NEED TO HAVE A UNLOCKED BOOTLOADER AS WELL!

For GAPPS, u can use the same or a updated version of the package. But has to be the same type u used to install it like (stock, full, Omni, basic, etc). ONLY FLASH/INSTALL IF the RESTORE SCRIPT DIDN'T SHOW UP during a DIRTY FLASH/UPDATE AND ONLY FLASH AFTER REBOOTING TO RECOVERY AFTER FLASHING/INSTALLING A OS/BUILD ZIP FILE!

How to get Platform Tools

These tools are used to install TWRP, to unlock the bootloader of your device and is needed to use the METHODS in this guide.

Download the platform tools.zip of your software platform (Mac, Windows, Linux)

Extract the platform-tools.zip

To use it go into your platform-tools folder

Press shift + right-click and choose command prompt or PowerShell

Connect your device when it's in fastboot mode and done

How to install TWRP

Sadly this Guide is for Windows, but other platforms like Mac or Linux can be found online.

YOU CAN USE THIS METHOD TO INSTALL A NEWER VERSION OF TWRP or ANY RECOVERY TOO

You need to have downloaded Platform Tools which the link is attached below.

Transfer the TWRP.img file into the platform-tools folder

If you want root download and transfer magisk.apk and the link is supplied below. Also, RENAME from .apk to .zip

Now we must boot into fastboot mode. (Either do it with the advanced reboot in developer options or power off device -> boot recovery Power + Vol + -> boot to bootloader or power off device -> press Vol Up + Vol down + power)

Now connect your device to a Windows device

Press shift + right-click. Choose command prompt or PowerShell

Enter "fastboot devices" and your device should be displayed if it's connected

Type "fastboot flash recovery_a twrpname.img " file name (do twrp + press tab) and press enter

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now choose to boot to recovery using the volume buttons

Enter the password and swipe to allow modifications

You have now installed TWRP and we've now checked that it has been successfully installed!

If you want root do this

Press the back arrow and find your magisk.zip

Swipe to confirm Flash

Reboot to the system and done

Otherwise, just reboot to system. Up to u

How to boot into EDL mode

This will have more than one method to boot into EDL mode.

Method 1

This is the basic method to boot into EDL mode

Turn off device

HOLD BOTH volume buttons

PLUG IN your device

Press the POWER button and CARRY ON HOLDING the volume buttons

You should be in EDL mode now

If your device still isn't in EDL mode try this

Open device manager in windows

Try the steps again

If not then try method 2

Otherwise, well done you have booted into EDL mode

Method 2

If you didn't manage to boot into EDL mode using method 1. If you can boot into system, do this method

Both methods will need you to download and install the All-in-one-tool from the download section

Go into developer options

Turn on USB debugging

Connect your device if u haven't

Press allow

Open the All-in-one-tool

Choose reboot EDL Mode

You should be in EDL mode now

Method 3

If you cannot boot into system and have bricked your device, try this method

This method uses TWRP to boot into EDL mode

IF U STILL CANNOT BOOT INTO EDL MODE and have bricked your device...

Install TWRP in the "How to install TWRP" section

Once you're in the home screen

Press reboot

Choose reboot to EDL

You should be in EDL mode now

Method 4

If you cannot boot into system and have bricked your device, try this method

This method will need you to download and install the All-in-one-tool from the download section

This method works if your on OOS or any ROM. Not after any failed attempt of wiping your device using MSM.

IF U STILL CANNOT BOOT INTO EDL MODE and have bricked your device...

Install TWRP in the "How to install TWRP" section

Once you're in the home screen, press reboot and choose the other slot (If ur current slot is Slot A then choose slot B and vice versa)

Reboot to system

If you're able to boot to the system

Skip the setup screen

Go into developer options

Turn on USB debugging

Connect your device if u haven't

Press allow

Open the All-in-one-tool

Choose reboot EDL Mode

You should be in EDL mode now

Installing a Custom ROM

Method 1

Follow the method suggested in the XDA thread. Stick to each method and follow the process!

If you want root and TWRP do this

Reboot to bootloader

Type: fastboot flash recovery_a twrpname.img

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now boot to recovery

Find the magisk.zip file

Flash Magisk

Reboot to system and done

Otherwise, just reboot to system. Up to u

Method 2

This method uses TWRP and isn't suggested in XDA thread of ROMs. I have tested this method with CrDroid and it works. BUT you will need a usb c OTG device (a device that can connect to ur phone via USB C) as this method will wipe ur internal storage

Transfer TWRP.zip, Build.zip (Custom ROM zip file) into internal storage.

Boot to Bootloader

Type: fastboot flash recovery_a twrpname.img

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now boot to recovery

Flash Build.zip (Custom ROM zip file)

Flash TWRP

Reboot to recovery

Flash Build.zip (Custom ROM zip file)

Flash TWRP

If the ROM doesn't have GApps included do this

Reboot to recovery

Flash Gapps if not included

Format data

Reboot to system

Otherwise, just format data -> reboot to system. Up to u

If you want root do this

Reboot to recovery

Flash Magisk

Reboot to system and done

Otherwise, just reboot to system. Up to u

Backing Up OOS and Custom ROM

Make sure u have installed the latest TWRP version from mauronofrio

You should use TitaniumBackup or Migrate to back up your apps and contacts.

Also, have a copy of your Internal Storage folders if u have important files.

TWRP Backup backs up your OS like Apps, settings and set up, but not internal storage.

NEVER BACKUP SUPER() for OOS! U CAN BUT IT COULD BREAK THE SYSTEM IF YOU RESTORE IT!

Restoring it makes going back way easier like you have never left :)

Or you can go manually and try and restore everything, but why do that when you got TWRP?

I do both ways of backing up

Backing up OOS

Boot TWRP recovery

Choose Backup

Choose boot, data (You can restore DTBO, EFS, Modem, but DO NOT BACKUP SUPER()) RESTORING SUPER() breaks OOS

Swipe to backup

Once done, either boot to system or mount

Transfer the whole TWRP folder onto a storage device

Done

Backing up a Custom ROM

Boot TWRP recovery

Choose Backup

Choose boot, data (You can restore DTBO, EFS, Modem, YOU CAN BACKUP SUPER()) BUT RESTORING SUPER() could break the ROM

Swipe to backup

Once done, either boot to system or mount

Transfer the whole TWRP folder onto a storage device

Done

Restoring OOS and Custom ROM

To restore OOS use MSM. Fastboot was the fastest and easiest way if u have a TWRP backup. BUT it doesn't work from my testing and only MSM successfully works.

Update: Fastboot ROM currently don't work under my testing. MSM is still the best way to restore to OOS and TWRP backups don't currently work. I don't recommend trying to use the fastboot ROM installer for OOS as you would have file transfer issues...

As of now, use MSM and just transfer what you have backed up. It's sad that TWRP backups don't work, u can try and post how it went. But for now, I don't RECOMMEND RESTORING OR USING TWRP BACKUPS!

I use MSM Download Tool restore for that. It will reset everything and will lock the bootloader. So, it makes for switching/installing a custom ROM a bit annoying.

DOWNLOAD FULL ZIP OF OOS version of your TWRP backup otherwise you could risk doing the whole restore method again OR setup from SCRATCH! IF you aren't restoring a TWRP backup, I recommend either TRANSFER or DOWNLOAD via WiFi or oxygen updater, a UPDATED version of OOS AFTER doing the MSM restore method. As they restore an old or different version of OOS!

Restoring using MSM Download Tool

Download latest MSM version

Extract/ un-zip

Click on MSM tool .exe file

Now we need to boot your device into EDL mode

Turn off device

HOLD BOTH volume buttons

PLUG IN your device IMMEDIATELY

Press the POWER button and CARRY ON HOLDING the volume buttons

If you cannot boot into EDL mode

Try the methods to boot into EDL mode in the "How to boot into EDL mode" section

Otherwise, carry on the method

Connect your phone

Wait for your device to be connected and it should show as green

Click verify to check and press start

Wait till phone reboots

The setup device and u can carrying on restoring your device if u don't want a unlock bootloader or return to what your device was like before. Or u don't have a TWRP backup

Restoring OOS TWRP Backup

If you have a TWRP backup of OOS, follow this method to restore your system data.

Go into developer options

Allow OEM unlocking

Reboot to bootloader

Enter "fastboot devices" to check your device is connected

Enter "fastboot oem unlock"

Swipe for yes

Then it will reboot again

continue to the next method

Once booted into system, set it up and update to OOS version of your TWRP backup.

Download the full zip using the link in the Download Link section.

Transfer the OOS .zip to internal storage.

Go into settings -> system update -> Update via local upgrade -> find zip file and press install

Do this twice to make sure you have installed that version of OOS in both slots

Boot to bootloader

Type "fastboot flash recovery_a twrpname.img " file name (do twrp + press tab) and press enter

Then press enter and type this: fastboot flash recovery_b twrpname.img

Reboot to recovery

Transfer whole TWRP Folder into internal storage

It is suggested to remove the SIM tray before you restore the TWRP backup and it can cause issues

Restore boot and data (You can restore DTBO, EFS, Modem, but DO NOT RESTORE SUPER())

Swipe to restore

Go to the next part to transfer your internal storage files + folders

If you have backed up your internal storage folders do this

Reboot to recovery

Transfer all your internal storage folders

Reboot to system and done

Otherwise, just reboot to system. U can update OOS as well if it's outdated. The method is below to update OOS with ROOT. Up to u

RESTORING TWRP BACKUP HAS ISSUES

You must remove your SIM tray before restoring the TWRP backup

Update: These methods were from my previous compilation guide for the Op6/6T. But as of now, TWRP backups aren't recommended for custom ROMs and I have only tested restoring TWRP backup for OOS. I haven't tested these methods myself nor know someone who has tested/recommends them for custom ROMs.

If u want to switch ROMs or unbrick your device I recommend using the MSM method in restoring with MSM section.

Restoring a Custom ROM TWRP backup 1

Restore fresh like you're going back to OOS.

Choose one method. Fastboot or MSM method.

I prefer the fastboot method.

Restore the device using MSM

Once booted into system, set it up briefly and DO NOT RESTORE ANYTHING.

Boot to bootloader

Type "fastboot flash recovery_a twrpname.img " file name (do twrp + press tab) and press enter

Then press enter and type this: fastboot flash recovery_b twrpname.img

Reboot to recovery

Transfer whole TWRP Folder into internal storage

Restore everything (System.img, vendor.img, boot.img and data)

Swipe to restore. If data couldn't restore then boot system, setup system, boot TWRP and restore data.

Reboot to system. The first reboot might go dodgy and it did for me.

Reboot to system and transfer all your internal storage stuff

done

If this did not work still. Then do the next method...

Restoring a Custom ROM TWRP backup 2

If the previous method has failed for you. Then try this.

Restore fresh like you're going back to OOS.

Choose one method. Fastboot or MSM method.

I prefer the fastboot method.

Restore the device using MSM

Once booted into system, set it up and update to OOS version of your TWRP backup.

Download the full zip using the link in the Download Link section.

Transfer the OOS .zip to internal storage.

Go into settings -> system update -> Update via local upgrade -> find zip file and press install

Do this twice to make sure you have installed that version of OOS in both slots

Boot to bootloader

Type "fastboot flash recovery_a twrpname.img " file name (do twrp + press tab) and press enter

Then press enter and type this: fastboot flash recovery_b twrpname.img

Follow the installation method suggested in the XDA thread for your ROM

Once it has been installed

Reboot to Recovery

Transfer twrp backup

Restore data

Reboot system. Done

If it still fails, repeat steps 1 to 18. But restore everything and you should be back on your custom ROM like you never left.

Updating OOS and Custom ROM

Update OOS with Root (Magisk)

Always do a TWRP backup before updating your OS in case

Update: As of now TWRP backups aren't recommended and haven't been tested, But this method works for updating OOS

Download the full zip file of the latest OOS, transfer the zip file to internal storage NOT IN ANY FOLDER

Go into settings, system update, update via local upgrade and choose the file

Wait till the installation has finished. If failed TRY AGAIN!

DO NOT REBOOT!

Go into Magisk Home

Press install

Press install via inactive slot

Reboot system and done

You will reboot into the next slot

If you want TWRP do this

Reboot to bootloader

Type: fastboot flash recovery_a twrpname.img

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now boot to recovery

Enter the password and swipe to allow modifications

You have now installed TWRP and we've now checked that it has been successfully installed!

Reboot to system and done

Otherwise, just reboot to system. Up to u

You don’t have to repeat the installation to install the latest OOS in the other slot. But you should and I use this method many times and has never let me down.

Updating OOS without root

Go to System Update -> find the update install and reboot.

Or download the zip -> transfer to internal storage -> update via local upgrade -> reboot and done

Update a Custom ROM

Follow the method suggested in the XDA thread. Stick to each method and follow the process!

Method 1

This method is for Custom ROMs that allows OTA updates and include GAPPS

Certain custom ROMs have this feature. Right now: Evo X

Go into settings, system update and press update

Wait till the installation has finished. If failed TRY AGAIN!

DO NOT REBOOT!

Go into Magisk Home

Press install

Press install via inactive slot

Reboot system and done

You will reboot into the next slot

If you want TWRP do this

Reboot to bootloader

Type: fastboot flash recovery_a twrpname.img

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now boot to recovery

Enter the password and swipe to allow modifications

You have now installed TWRP and we've now checked that it has been successfully installed!

Reboot to system and done

Otherwise, just reboot to system. Up to u

Method 2

This method is for Custom ROMs that allows OTA updates and don't include GAPPS

Certain custom ROMs have this feature. This method is for vanilla ROMs: CrDroid

Go into settings, system update and press update

Wait for the update to download and Press install

Wait till the installation has finished. If failed TRY AGAIN!

Press reboot

Done

If you want TWRP do this

Reboot to bootloader

Type: fastboot flash recovery_a twrpname.img

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now boot to recovery

Enter the password and swipe to allow modifications

You have now installed TWRP and we've now checked that it has been successfully installed!

Reboot to system and done

Otherwise, just reboot to system. Up to u

Method 3

For Custom ROMs that don't have OTA updates.

Follow the method suggested in the XDA thread. Stick to each method and follow the process!

Before the last step which is to reboot to system...

If you want root and TWRP do this

Reboot to bootloader

Type: fastboot flash recovery_a twrpname.img

Then press enter and type this: fastboot flash recovery_b twrpname.img

Now boot to recovery

Enter the password and swipe to allow modifications

You have now installed TWRP and we've now checked that it has been successfully installed!

Reboot to system and done

Otherwise, just reboot to system. Up to u

Download Links:

All in one tool Here

SDK Platform Tools (Fastboot Tools) Here

OOS versions for OP8Pro (under Signed Flashable zips) Here

TWRP for OP8Pro Here

Magisk Here

NikGapps Here

MSMDownloadTool for OP8Pro Here

TitanumBackup App Here

Migrate App Here

Credits:

@infected_ For your amazing work on the TWRP recovery and method to install TWRP

@osm0sis For your amazing work on developing a version of TWRP that allows flashing

@mauronofrio All in one tool

@topjohnwu For his work on Magisk

@Nikgapps For their work on creating Gapps

@Some_Random_Username For his Collection of MSMDownloadTool for OP6/6T

@OPTeam For the collection of OOS zips for OP8Pro

@BillGoss For his help to restore TWRP backup on the 8/8T Series