Connect the USB to a USB 2.0 port (USB 3.0 often won't work for flashing). Go to Settings > System > Local Update and select the drive.
There are two primary methods for installing a new image on a Hi3798MV100 device. This is the safest method for functional devices. hi3798mv100 firmware
Open the box and connect the TX, RX, and GND pins of your adapter to the corresponding pads on the motherboard. Connect the USB to a USB 2