The demo trigger might be in the bootloader. Connect to a PC and run: adb shell settings put global device_demo_mode 0 Then repeat the recovery reset.
: Open the Phone app and dial *#899# . This opens the Engineer Mode or factory test menu where you may find "Manual Test" or "Device Debugging" options to disable retail features. oppo demo mode remove
Contact Oppo support or authorized service center with device identifiers (IMEI, serial) and request demo-mode conversion; follow their instructions. If official route not available, continue with caution: The demo trigger might be in the bootloader
: If software methods fail, power off and hold Volume Down + Power to enter Recovery Mode . Choose Wipe Data , though this may not always remove deeply embedded retail firmware. This opens the Engineer Mode or factory test
Some Oppo devices have a built-in option to disable demo mode. To check if your device has this option: