So my mac HD started playing up and then refused to work, would not boot.
Tried recovery mode but it wouldn't allow me to run first aid on the Macintosh HD drive.
Created a MacOS USB boot up stick by formatting a blank USB stick then using the recovery option to install MacOS on it.
Plugged it in, rebooted and held the command (cloverleaf) key.
Mac then displays the drives from which you can boot
Chose the USB stick and not MacintoshHD.
and it is taking forever.
It took me through all the usual options "set up appleID" and so on which I either skipped or chose default.
Then it just went black with the beachball.
Now it's just black with the arrow/pointer.
Doesn't appear to be doing anything..
So is it because MacintoshHD (internal HD) has issues that the USB booter is not able to finish?
EDIT: additions in italics