Error code F3

We sincerely apologise for the inconvenience caused.
If you could kindly follow the steps below to perform a reset, we would be most grateful — this may resolve a temporary error.
Reset procedure:
First light up the screen, then press the DISPLAY button 6 times, and then press and hold it. When the screen shows 【021 011】, the reset is successful.
The screen will first turn off, then relight and display the remaining battery level — your device is now reset.