This is the easiest and safest method, but it only works if your current recovery is not corrupted.
The problem arises during step 3. Instead of using the official OPPO ColorOS ROM (specific to the model number like CPH2483 or CPH2479), some refurbishers use: oppo a78 refurbished firmware
The firmware includes a Dynamic Computing Engine to reduce lag and jitters, alongside 48-Month Fluency Protection to ensure the device remains smooth over long-term use. This is the easiest and safest method, but