To use a USB flash drive to perform a recovery, you must select the drive in the Boot Menu upon system startup. To change the default drive, do the following:
Turn on the computer and immediately press the Esc key repeatedly, about once every second, until the Select Boot Device screen or the Boot Order Menu opens.
On desktop computers
, the Startup Menu opens. Press F9
to open the Boot Menu.
Figure : Startup Menu on desktop computers
Use the up or down arrow key to select the USB drive, listed under Legacy Boot Sources. Then press Enter.
On notebook computers, the Boot Option Menu opens. Use the up or down arrow key to select the USB Hard Drive, and then press Enter.
Figure : Boot Order menu on notebook computers
Your computer will now automatically boot to the recovery media in the USB drive when it is turned on.