My brother in law has a MacBook Pro, mid 2012 model. He'd been having problems with it in that it would boot to the login screen, but then wouldn't finish booting. After putting in the password, it would go back to the grey Apple logo screen you seen at boot (but no progress bar or anything) and just sit there forever. I took it home and made a backup of the drive and while doing that, found that both Carbon Copy Cloner and Disk Utility indicated the hard drive had some sort of physical problem. So he took the opportunity to get an SSD for the MacBook with the intention that we'd do a fresh Sierra install and manually move over photos, documents and such. I have tried several times now to do this. I've tried a couple of times by installing the new drive, booting from a bootable USB installer thumb drive and initializing the new SSD and installing Sierra. It gets to about a minute left and hangs, even overnight. So I tried running the installation on my Mac using the thumb drive as well. This time the installation worked, I set up the user account and booted up from the new SSD on my iMac. But when I moved the SSD back to the MacBook, it wouldn't boot. Gives me a no entry sign and a folder with a question mark. So I recreated the bootable installer drive using Diskmaker X this time, erased the SSD and tried again on the MacBook Pro. Again, it hangs at about a minute left. What am I missing here?