In the future, your computer will first check the USB port for boot media when starting up.
If you do nothing, your computer will go to the next device in the boot sequence list, which will likely be your hard drive.
The boot order tells the machine which devices to search for the software needed to launch the computer and the priority each device in that search. That’s because the BIOS settings include the boot sequence the machine follows when starting up.
Starting your PC using USB rescue media is not difficult, although it first requires an adjustment in the BIOS (Basic Input Output System). The Startup Manager only lists drives that include bootable content. NOTE: Have multiple USB devices connected to your Mac? Don’t worry.
The machine will start to boot from the USB drive.