Oppo A91 (CPH2021) REPAIR STAGES...
1- ADVANCED PARTITION MANAGER (BACKUP ALL EXCEPT SYSTEM AND USERDATA)
2- If Android version 10 is installed;
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3- If Android version 11 is installed, download the firmware from the link below and select only Scatter from the MEDIATEK -> FLASH tab with DFTPRO, remove [opporeserve1 opporeserve2 opporeserve3] from the incoming sections and install it on the device.
Firmware : *** Hidden text: cannot be quoted. ***
After the process is finished, apply the Android version 10 method...