Hi there,
You need either a micro usb cable with pin 4/5 shorted on micro usb plug or a USB OTG cable with male to male usb plugs. (hardware requirements)
Next step (if not done already): Install Direct USB (I prefer DUSB Universal)
http://dc.p-mc.eu/tools/directusb/download
Install the driver (you can find it inside the driver folder of the 7z archive) as "legacy hardware" through windows device manager (some windows versions require you to disable driver signature enforcement)
Now you can use Direct USB to flash .elf binaries: Connect your dashcam, press "Connect", select a7 platform, your firmware binary and press "Download". Thats it