Error code F5

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