Those "drivers" you have been experimenting with are firmware updates. Firmware updates write to a chip the writer itself in order to change certain properties of the drive itself. If something goes wrong when one of those firmware updates is writing to the chip in your drive, you can end up with a drive that doesn't work properly. This may be what happened in your case when you tried to flash the drive back to a GWA-4164B, particularly if you interrupted a flashing process before it completed.
I can give you links to GWA-4164B firmware but the flashing programs inside usually will check to make sure that they are only run on a drive with the same model number. So if you try to run GWA-4164B firmware on your current drive, it will probably identify your drive as a GSA-4166B and refuse to work. The firmware program you originally used to cross flash your GWA-4164B to a GSA-4166B was special because it did not perform that check. So it may not be possible to go back to a GWA-4164B.
These two links may have firmware for the GWA-4164B which you can try to use. The firmware updates may or may not work as I mentioned above :