If you're trying to install using the method of putting the loader USB in prior to boot, and powering on and it says it's installing the games, and says successful but gives the authentication error when you reboot.
Use the "better" method IMHO. If you're getting the error, clear it first. Boot normally with the ekey and diag key in. Remove all the games that were installed so it's just as it was before you loaded the new games.
Clear NVRAM and Safe Storage in the Diag and reboot. Yes, you'll need to setup again, but you won't need to wipe the SSD.
It should boot normally into setup. Complete a basic setup with at least one game. When you are back up again booting normally as you shouldn't get that error anymore, install games by putting in the ekey after a normal boot, and install each game that way.
Exactly what I did and it resolved the error and all the games I loaded with the ekey after a normal boot were all good to go then. I also only load one game on USB at a time, not a bunch on the same USB key. USB keys are cheap. But that's just my preference, I didn't try with many games on one USB.
If you switch to another SSD and it boots normally, you of course don't need to do the "fix", just load games after a normal boot using the ekey.