"System" dancing on screen indicates it IS in preboot but it will only stay in that for a couple of seconds unless a flash is initiated. Once a flash starts properly it'll be fine. To have any chance of catching it, you need to do it like this:
  • Open the firmware file in Updater.exe and enable the Radio Button next to 'USB Device'
  • Ensure device is fully OFF (not in standby)
  • Connect a 'known-good' USB cable directly to a REAR USB2 port (not a USB3 or front port or thru' a hub)
  • Hold the screen firmly over the 'G' and plug in the device to the cable while watching the GUI
  • IMMEDIATELY the device's detail appear in the window adjacent to 'USB Device' on Updater's GUI hit 'OK' or hit the PC's 'Enter' key (be VERY quick)
  • Hold the screen until the flash finishes by Updater giving the 'success' message.