Method Fix Power Off Not Working (Unlock Your phone For more options).
Note: The formatting process will delete all phone data, and you have to be sure of an email and password before formatting it because most devices ask you for the same email used before formatting, What is meant here by email is the account used in the Google Play Store or deleting the Google account from the settings before formatting.
The method is to format the oppo via recovery:
First, we turn off the device completely, pressing for a few seconds the Power button + Volume Up button.
Once a black screen appears press and holds the Volume Down button until Recovery Mode:
Click on English:
Click On Wipe Data:
Click On Format data: Add the code shown on the screen. And click Format.
Finally.