Problem flashing dual partition device - Oneplus 9 - question about recovery

[z0m8i3]

Followed the instructions here: https://wiki.lineageos.org/devices/lemonade/install
When it came to recovery, I opted for TWRP instead, as that's what I've always used & am most familiar with for my Lineage devices.
Followed TWRP steps here: https://forum.xda-developers.com/t/recovery-11-official-teamwin-recovery-project.4294289/

Instantly bricked, but could still access fastboot. No error saying flashing failed or anything.
So then, I tried flashing Lineage's recovery - that made things worse and ended up on Qualcomm Crashdump. fastboot only worked if the phone was unplugged from my computer's USB, for some reason.

My tools:
- Debian Bullseye
- Fastboot v28, tried backport version v29 - same results

Relented and followed the instructions from the install page, regarding the A/B issues with fastboot:

Note: Outdated fastboot releases dropped legacy A/B support, so it might attempt to flash to boot__a / boot__b rather than boot_a / boot_b if you try to flash boot. In this case, you must update fastboot to a release newer than or equal to 31.0.2. Alternatively, you can manually specify which slot to flash to based on what slot fastboot failed to flash to. For example, if fastboot fails to flash to boot__a, you must flash to boot_a.

Success... except I still got Qualcomm crash and couldn't do anything on the device.

FYI, I ran:
fastboot flash recovery_a lineage-19.1-20221204-recovery-lemonade.img

This is my first time flashing an A/B device and the first time I've had such weird issues with flashing Lineage, I believe my problem is related to the fastboot flash recovery_a lineage-19.1-20221204-recovery-lemonade.img - but before I attempt flashing again, I'd like to know for certain what to do in this instance.

Was I supposed to also do:
fastboot flash recovery_b lineage-19.1-20221204-recovery-lemonade.img
?

Or, is something like fastboot --set-active=a required at some point?

Searching for others' instructions in this scenario is a bit tricky as all of the guides are written for Windows and clearly I'm an outlier doing this on a Linux box.


If anyone else comes across this after bricking their Oneplus 9, I got it back up and running on Oxygen OS by following this article: https://www.droidwin.com/unbrick-oneplus-9-pro-fastboot-commands/ and used: https://github.com/ssut/payload-dumper-go to get payload.bin extracted from the zip I downloaded from: https://www.oneplus.com/support/softwareupgrade/details?code=PM1617074715494
all while sitting on Linux, did not need to involve a Windows machine at all.


Thanks in advance for any insight anyone can offer!

 

[z0m8i3]

Gave this another shot and believe I figured out what I did wrong..

• Phone was on Android 11, I did not go through incremental updates
• Following Lineage's instructions, I flashed dtbo.img and vendor_boot.img -- take note that the latest are --Android 12--, so presumably, this caused the device to choke

After getting it unbricked and back on Android/OxygenOS 11, I did the incremental OTA updates to get on Android 12, then proceeded to flash the Lineage instructions exactly as before, except I went with Lineage with MicroG and used their recovery (offered on the device downloads page).

Everything went smooth this time around and I'm now on Lineage!