Probable causes and solutions:
1. If the connection of the USB data cable is abnormal, check whether a notification indicating that the USB cable is connected and the connection type is selected is displayed in the notification bar. If not, the USB cable may not be connected properly. Remove and reconnect the two ends of the data cable, and replace the USB port or data cable. Note that some non-standard charging cables are used as data cables.
2. If the driver is not installed or is abnormal, please check whether there is a notification indicating that the USB is connected and the connection type is selected in the notification bar. If the driver mode is selected, a CD-ROM virtual CD-ROM device will be added on your computer. Please re-install the driver file and restart your computer.
3. If the connection type is not set correctly, check whether there is a notification indicating that the USB device is connected and whether the connection type is selected in the notification bar. If yes, select the file transfer mode.