[OnePlus 7 Pro Guides, News, & Discussion] Sugaaa:
Foolproof method to install roms, twrp + root.

Read through the directions first before you start anything and your phone wont get bricked. Even if it does, you can use the msm tool guide that I linked below to restore it and get it prepped up for custom rom install again.

Pre-requisites:

1) Update to latest android 11 through software update.

2)Have oneplus drivers and adb/fastboot drivers installed

[TOOL]Minimal ADB and Fastboot [2-9-18]

Introduction ADB and Fastboot are arguably two of the most indispensable tools used when working with Android devices. If you really want to modify, debug, and tweak along with their countless uses in rooting, and other procedures ADB and...

xdaforums.com

Download TWRP unofficial for oneplus 7 pro android 11 here and move it into minimal adb and fastboot folder

https://xdaforums.com/t/recovery-11-unofficial-teamwin-recovery-project.4289455/

3a)Download Magisk v23.0 if you want root

Releases · topjohnwu/Magisk

The Magic Mask for Android. Contribute to topjohnwu/Magisk development by creating an account on GitHub.

github.com

3b) Move custom rom into internal storage like download folder for custom rom install

if you have issues with fastboot not recognizing device or other driver issues, click this link https://www.droidwin.com/fix-android-device-not-showing-in-fastboot-mode/

*****Extra Steps Required for T-mobile variant for installing custom roms****

-I tried everything and couldnt get havoc os to install on my t-mobile variant. It would always end up in a bricked state. To get around this, you first need to convert it to international following this guide then follow steps below after you have kept updating it in system until there are no more updates available. https://xdaforums.com/t/guide-how-to-convert-tmobile-op7-to-international.3935947/

Guide for installing custom rom over android 11

-unlock bootloader and enable usb debugging then connect phone- use this video on how to unlock bootloader but dont follow his other steps yet

-open up cmd in minimal adb and fastboot folder and type in adb devices and make sure phone shows up

-in cmd, type in "adb reboot bootloader"

-in cmd, type in "fastboot devices" and make sure phone shows up

-in cmd, type in fastboot boot "name of your twrp file"

It should boot into twrp. at this point, you should have your rom zip file in the internal storage

-install the custom rom.zip. In my case, i installed havoc 4.8. After thats done, go back to wipe and format data. For extra measures, go to wipe and advanced wipe and wipe dalvik cache, data and vendor then reboot.

-to get root, set up the phone and enable usb debugging again. Transfer magisk v23.0 to download. adb reboot bootloader and go into recovery if your rom has one(havoc has its own) or fastboot into twrp again and install magisk. At this point, you can also install twrp if you want. Follow the guide above to install the unofficial twrp.

Guide for installing TWRP and root on official android 11

-unlock bootloader and enable usb debugging then connect phone- use the video above on how to unlock bootloader but dont follow his other steps for twrp yet

-open up cmd in minimal adb and fastboot folder and type in adb devices and make sure phone shows up

-in cmd, type in "adb reboot bootloader"

-in cmd, type in "fastboot devices" and make sure phone shows up

-in cmd, type in fastboot boot "name of your twrp file"

It should boot into twrp. at this point, you should have magisk v23.0zip in your internal storage like in download folder if you want root

-go to advanced then flash current twrp

-then install magisk v23.0 and you're done