I put #3 hd in the 8500 and restarted it to insert the Rescue CD
but it would not read the CD and I tried several times. It just goes
straight to the login and then I got this.

https://postimg.cc/8fJxW3wz

Then after pressing enter/escape it finally went to the desktop. We
need to resolved this invalid install issue. As you saw for yourself'
the 8500 is licensed so I don't know why I'm getting this or why the
external HD are messing up when it was fine or why the Rescue CD
doesn't load.

The external hd case had no issues on the 780 but I replaced everything
including the hd and it still won't fucntion yet the Mrimg hd and flask key
do?

At present #3 is on the 8500 and I'll leave it here for the time being until
I hear back from you.

Robert