This works for the pro-668, psr-800, ws1080 and similar scanners.
You must have the comport driver for your scanner model installed and working on your computer or you will not be able to do this.
Unplug the scanner from the USB cord. Take out the batteries. Let it sit for awhile. Put the batteries back in. It should go back to a blank screen.
DO NOT TURN THE SCANNER ON!
Plug the USB cord into the scanner. DO NOT TURN THE SCANNER ON! Plug into the PC. An icon should appear on the bottom of your PC. It will show that the USB cord has connected. Bring up the EZScan/iscan software.
At the very top of the software, click on Updates, click on Check for all updates. Allow it to do all updates and upgrades (unless on unofficial hacked firmware). The scanner will tell you when it's finished. DO NOT UNPLUG THE USB CORD. When all updates/upgrades have finished, click on done/finished in the software. Then click on the icon and click on remove safely. Then your scanner should work.
Link to Radio shack Pro-668 standalone installer for Cpu version 2.4 (I have not tested this this) Please let us know that it works.
https://drive.google.com/file/d/11EqRvEuICcz5C4qxdp6XL1fb6zYUk5qb/view
Link to Radio shack Pro-668 standalone installer for Cpu version 2.5
https://www.dropbox.com/s/yusta63b8mduwb6/PRO668Updater_2.5.0.357.zip?dl=0&file_subpath=%2FPRO668Updater_2.5.0.357.exe
LEGACY stand alone cpu firmware installer for Scanner that have been sent to whistler for the Legacy upgrade to a WS1080
https://whistlergroup.com/pages/legacy-downloads