Some time ago, I went and installed ElementaryOS on my Samsung NP530U3C. After that, I could never access the BIOS again. Pressing F2 had absolutely no effect (neither any other common BIOS-accessing key, such as F10, Del, Tab...). Actually, neither F4 (recovery) nor F10 (select boot device) has any effect.
The only way to boot from an USB now is to mash F buttons until it happens to boot (without any 'select device' window, it just boots the USB). It booted to the installed OS just fine.
A few days ago I thought I could try to reset the BIOS to factory settings (by disconnecting the CMOS battery for a while), and see if that enables me to enter the BIOS again. Well, it didn't, and now the notebook does not boot at all. Upon startup, it shows the Samsung splash screen, it restarts, and the "Boot Menu/App Menu" appears without any options whatsoever.
I tried using the boot-repair ISO USB disk, and when trying the Recommended fix, it says that my notebook is in Legacy mode, and that I should change it to UEFI. I would gladly do so, if I could access the BIOS...
So, I thought if there would be some way to change the boot mode to UEFI by software, or add the "Setup" option to the "App Menu" (usually, these notebooks have this 'Setup' option there, which loads up the BIOS menu). Well, any way to fix this I will gladly hear.