I’ve gotten this to work, there are basically 3 issues, see here and its link: http://forums.sandisk.com/t5/SanDisk-ReadyCache-SSD/Solve-my-Win10-ReadyCache-issue-early-Win10-upgrade-user/td-p/347672
The Win8.1 to Win10 upgrade for early adapter can possibly cause the folder to be removed, solution is to copy the files from the Windows.old path and attempt a manual fix above. There is possbly some interference from the account permission, so you need to STOP the ExpressCache service so that it would uninstall fully. This doesn’t appear to happen with a Win 10 upgrade THEN putting in the ReadyCache after. If you don’t have the Windows.old file, Sandisk support can provide that, they should just put up a download link for it, I’m not gonna do it because I dont’ work for Sandsik.
You need to remove as many files as you can from your %tmp% path before you start, for some reason the extractor doesn’t overwrite the files OR is picking up some old files from the %tmp% path, and the installation will go wrong. (in my case, eccmd returns license issue AND ExpressApp launch issue). While you are at it, delete the Condusiv folder under Program Files as well just to be clean.
You want to delete of the partition on the ReadyCache drive, after the installation you will see a new partition being created, that’s usually a good step to verify if the installation is even working.
Hope these tips would help. It took me a long while crawling numerous forums and finally solved this.