To clarify BEFORE you upgrade you need the comport driver for that model scanner ex
ro-18, Pro668 or Psr-800,
After the upgrade it is a WS1080 so you need the ws1080 driver. So 2 different drivers are needed and you will need to install both.
One to start the upgrade (it is most likely already installed if you have previously used ezscan to update the firmwares or set the clock). The second the ws1080 to install the dsp firmware and set the clock.
You should have both of these drivers before you begin the upgrade.
The key here to know if the driver is working is to try and set the clock via the iscan then again in ezscan. if it won't set then the driver is missing or corrupt and MUST be fixed BEFORE you go any further. It is irrelevant that you can see the Micro SD card as that driver is not the one needed to talk to the CPU and complete the firmware upgrade.
In order to fix the driver you either need to install it or uninstall then delete all files for it followed by a reboot, then reinstall using the proper procedure for your OS.
For win 10 that means the procedure for allowing UNSIGNED driver MUST be followed. (google it)