[Oppo Reno Ace Guides, News, & Discussion] 工藤新にゃん:
I'm not the author of this ROM. I just saw that there was no post in the ROMs area of this model, so I thought this model had no ROMs based on AOSP, but I saw that there was ROM of this model on the official website of ArrowOS, so I sent this post to inform you

The download link is https://arrowos.net/download/OP4A89

The author is Coolapk user Art_Chen

(I try to share the flash process)

Method 1 (conventional method)

Need to downgrade to ColorOS 7 first

downgrade tool https://img-oppo-cn.oss-cn-hangzhou.aliyuncs.com/uploads/util/2022/02/23/1645585834165.zip

or https://cloud.189.cn/t/qeqUbeb2i2ee

Then apply for Depth Testing and wait for it to pass

Once passed, the developer option enables OEM unlocking

Reboot to fastboot

Download platform-tools and unzip it

Open the CMD and go to the unpacked directory

Input "fastboot flashing unlock" and press enter

Press the volume key to select "Unlock The Bootloader", press the power button to confirm

After Unlock is done, reboot to fastboot again

Flash the TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img or TWRP for ColorOS 7

(For example TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img )

Put the "TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img" file into the platform-tools directory

In CMD Input "fastboot flash recovery TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img " press enter

Press the volume keys to select RECOVERY MODE and press the power button to confirm

Set the language and swipe

In TWRP use the regular method to flash ArrowOS and Wipe (Format data)

Method 2 (the method I have tried)

In ColorOS 11 apply for Depth Testing and wait for it to pass

Once passed, the developer option enables OEM unlocking

Reboot to fastboot

Download platform-tools and unzip it

Open the CMD and go to the unpacked directory

Input "fastboot flashing unlock" and press enter

Press the volume key to select "Unlock The Bootloader", press the power button to confirm

After Unlock is done, reboot to fastboot again

Flash the TWRP for ColorOS 11

(For example TWRP-3.6.0_11-RenoAce_by_Art_Chen-ColorOS11-Firmware.img )

Put the "TWRP-3.6.0_11-RenoAce_by_Art_Chen-ColorOS11-Firmware.img" file into the platform-tools directory

In CMD Input "fastboot flash recovery TWRP-3.6.0_11-RenoAce_by_Art_Chen-ColorOS11-Firmware.img " press enter

Press the volume keys to select RECOVERY MODE and press the power button to confirm

Set the language and swipe

If can't read or write the internal storage, format the data

TWRP main screen → Wipe → Format Data → yes√

TWRP main screen → Reboot → Recovery

If still can't read or write to the internal storage, Need to create a media directory in data

TWRP main screen → Advanced → Terminal

Input "mkdir /data/media" press enter

Copy the ColorOS7 firmware from computer to phone

(For example firmware_c27.zip)

TWRP main screen → Install → Select "firmware_c27.zip" and swipe

( may need to look for files in the directory /data/media/ )

Copy recovery TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img or TWRP for ColorOS 7 from computer to phone

(For example TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img )

TWRP main screen → Install → Bottom right "Install Image" button → Select "recovery TWRP-3.6.2_12-RenoAce-A12.1-Only-by-Art_Chen.img" → Select Partition Recovery and Swipe

After done, TWRP main screen → Reboot → Recovery

Now you can use the regular method to flash ArrowOS and Wipe (Format data)