I know one other thing you could try. If you can determine when the Toolbox was on the Intel website and operational you could go on the Internet Wayback machine and see if they stored the site. Might not work, but I know other people said it worke...
You can still find SSD Toolbox on some third-party sites; e.g. ...
Intel SSD Toolbox 3.5.15 Free Download for Windows 10, 8 and 7 - FileCroco.com
As always, be careful with third parties!
SSD Toolbox has been replaced:
"Intel's SSD Toolbox has been the primary maintenance program for Intel SSDs for almost a decade, but the company is finally winding it down and replacing it with a newer app called the Intel Memory and Storage Tool."
