Use a python-based tool like mtk-client to force the device into BROM mode (usually by holding the "heart" or "back" key while plugging it in) and unlocking it.
Delete pre-installed Chinese apps that drain battery. qin f21 pro rom
The stock firmware (especially the Chinese version) is designed for extreme minimalism or parental control. By switching to a custom ROM, you gain: Use a python-based tool like mtk-client to force
If the physical keys don't type correctly, you may need to install the "QinPad" APK or a similar T9-compatible IME. qin f21 pro rom
Data interruptions during flashing can "brick" the device. How to Flash the ROM (High-Level Steps)