I would start from scratch if I were you. Assuming you have OOS 10 installed and not OOS 11, this is what I did:
- Boot to TWRP (using fastboot boot)
- Format data
- Reboot to bootloader
- Boot to TWRP again (using fastboot boot)
- Flash OxygenOS 10 + TWRP and reboot to TWRP (1/2 - first slot)
- Flash OxygenOS 10 + TWRP and reboot to TWRP (2/2 - second slot)
- Reboot to system once in order to update firmware
- Boot to TWRP (using fastboot boot)
- Format data
- Reboot to bootloader
- Boot to TWRP (using fastboot boot)
- Flash ResurrectionRemix + TWRP
- If you chose GApps variant, reboot to system
- If you chose Vanilla variant, flash GApps (NikGApps core worked fine for me) and reboot to system
- Reboot to TWRP and flash Magisk
- Reboot to system
If you're on OxygenOS 11, first you need to downgrade to OxygenOS 10. There are several methods to do so, you can use MSMDownloadTool (check
this thread). As far as I'm concerned, I formatted data from TWRP and flashed the downgrade zip that I downloaded from
here (ensure you download the 7 Pro zip, not the regular 7 one). The other link I originally found is
dead as I'm writting this.
I flashed it from TWRP because I couldn't install it from OxygenOS updater for some reasons (Settings > System > System), I kept getting "System update instalation failed" error.
Good luck!
I think there is something fundamental I (and others) do not understand about the A/B partitions, the /Data partition, and the way TWRP and fastboot manage these.
I would really like to know how best to install the updates for RR *without* losing root and TWRP, and (less importantly) all my theming, but even trying to do a clean install or a simple(!) TWRP restore seems fraught with difficulty.
If I am running a ROM on slot A, and I boot to recovery (TWRP), and I do a restore.. which slot is that restore going to? If I do an install of a .zip (different ROM), that seems to go to slot B (whichever slot is not active). The problem seems that I get all sorts of weirdness with the /Data partition. What's going on there? It disappears, gives things like error 255, etc.. After installing or trying to restore a backup, I get a boot loop and then don't really know how I end up getting out of it. I'm doing various things like re-formatting /Data to ext2, then setting it back to ext4. I get errors where I cannot boot to TWRP from fastboot... etc. etc. Then, slowly, I manage to get out.
One crucial question here: when/what causes the system to switch slots if I do not do it manually via TWRP or fastboot? After I restore a backup, does TWRP switch slots? After I install a .zip (ROM, Magisk, gapps, etc.) is the slot toggled?
Here's an experience I had:
1. I was trying to re-size my custom boot animation (I did not create it, just want it to fill the screen). I ended up in a boot crash. Ugly looking 'crash dump' error.. blah blah.
2. Powered on with PWR+VolDn, entered TWRP, selected my backup and restored. Presto! Back in business.
3. I saw the RR updater had a new update.. ran it and let it do its thing per 'the documentation'.
4. Found I had no root, no TWRP, and no themes.
5. Ran fastboot.. booted from the external (on PC) TWRP image, selected my backup, restored it.
6. Boot loop, and things just got worse from there.
What went wrong in #'s 5 and 6, and why did that not work like #'s 1 and 2?
How can these problems be avoided? What is actually going on? Why is this anything but simple and easy?