If the update does not start after the message "Please connect USB storage device into top USB1 port" is shown, please check below items.
1. Did you format the USB device using FAT or FAT32 format?
If you use FAT32 for formatting on your Mac, please select Master Boot as shown below when you format the USB stick.
2. Is the unzipped update file copied to the root directory of the USB device?
3. Please make sure the file name is exactly the same as shown in the Firmware Update Guide. If you run the file with only one different letter, it will not work.