I will attempt to preserve this so simple as attainable but it surely’s slightly difficult.
I’ve two MacBook Execs, which I’ll name “Outdated MBP” and “New MBP.” Outdated MBP has an issue, most likely a nasty onerous drive, and so I am attempting in addition it up from an exterior drive. To do that, I want to put in Excessive Sierra (which is the latest model of macOS that Outdated MBP can run, on an exterior drive. New MBP, nonetheless, is working Mojave, so I can not run the Excessive Sierra Installer on New MBP. So I created a bootable USB installer for Excessive Sierra, restarted New MBP with it as my startup disk, and tried to put in Excessive Sierra on the exterior drive. This gave the impression to be working till the set up hit the purpose when it needed to restart. At that time, New MPB booted to its inside drive, so the set up of Excessive Sierra on the exterior drive did not end. Now I’ve a folder on the exterior drive known as “macOS Set up Information” however I do not know how you can get it to finish the set up on that quantity. Are you able to assist?