Error code F3

We sincerely apologise for the inconvenience caused.
Please reset the device and then charge it using a standard household power socket for at least 30 minutes before checking whether it resumes normal operation.
To reset the device, press and hold both the power button and the USB button simultaneously for five seconds. The screen will briefly turn off and then relight, displaying the battery percentage and other information — this confirms that the reset has been successfully completed.