Creating a USB Install Disk - Sierra

Hello,

My iMac recently ran into a kernel panic problem. I decided I was going to restore from a backup, but accidentally restored it from the wrong backup - a backup that doesn't belong to me.

I resigned myself to having to format and start over, but none of the options from the recovery menu work. When I try to redownload the OS, it will process for a few hours then give the error "OS X could not be installed on your computer"

The only instructions I can find are four years old and no longer applicable to the app store, as far as I can tell.

Please help!