Here the HP uses F9 to select the boot drive. But what is this about a lock screen. If it's locked, the PC may be locked out of getting to the BIOS so you often have to unlock it, let Windows or such boot and then get to the BIOS via W10.
HP Pavilion P20 AIO Desktop, Win10 Home. Am unable to get into BIOS;have tried every usual way(Esc, Del,F12,F8,F6,F2,F1) several times each key. Went to HP P20 site, followed exactly what they said, still didn't work. I've tried to boot with: gParted, other Linux disks, Win10Disks, however, each time it opens with the lock screen page. BTW-I'm wanting to access BIOS to make sure 1st boot is DVD Drive, 2nd is HDD. Also, as the is an all-in-one computer, taking it apart and replacing hard drive is NOT an option. I would sure appreciate any suggestions. Thank you.