If the BIOS is password protected (and you don't have the password), and it's locking out changing the boot order, usually F12 during POST is the only option you have. If you can't use the F12 ...

I have a Dell R410/R610/R710/R815/R910 Press F11 and you will enter the bios boot selection. Under disk drives (or something similar), you should see your USB device.

The BIOS (Basic Input/Output System) on your PC controls fundamental operations, such as guiding the computer on how to boot ...

Restart your Dell computer. Watch the screen for the blue "DELL" logo. As soon as you see this, press the "F2" button. After a few seconds, the BIOS screen will appear.

If your Windows PC keeps booting into BIOS, it could be due to incorrect BOOT Sequence, damaged or loose SATA cable, misconfigured BIOS settings, etc.