Fortiswitch 424E upgrade failing

I am trying to upgrade the firmware on our Fortiswitch, current version 6.4.1. I downloaded the firmware for Fortiswitch 424E:

When I click on apply, I get a message the message "there is already an active admin session for this browser".  I am the only user logged in and I tried clearing the cache and browsing history in the browser. The upgrade never succeeds or completes after this message comes up.

I tried logging in via putty to a ssh session but did not find a way to upgrade the firmware via cli. There is a way to verify the image but I did not find a method for actually upgrading the firmware.

Has anyone run across this before or know of a way to upload the firmware via cli?