For firmware updates you have to use the USB port next to the SD card slot on the craft .
Although it says "connected", it's acting like it's not connected. Have you tried a different cable? Some USB cables (very few) are charge only, you need a data connection cable. You may have a bad cable too, even though it's new. Test it on something else and transfer a file to a computer or something.
Have you ever updated this craft before, or is it brand new? Why are you trying to update it? Doesn't the craft fly? Have you tried to connect with your iPad or Android tablet? Have you tried to fly it? Have you looked at the firmware version in the ABOUT section of the GO4 app when connected wireless, as if you're ready to start the motors?