Need help entering BIOS, Sony Vaio SVT13125CXS

[jhu]

As the title says, how do I enter the BIOS on this thing? Why do I need to do this? Because, silly me, I changed the boot setting from UEFI to Legacy boot, and now I keep getting "Operating System Not Found". I press F2, F10, Delete, nothing works. I just need to change it back, but there's no message saying what button to press. It starts with a VAIO logo and immediately to "Operating System Not Found". Help!

 

[jhu]

Ugh, now I tried different hardrives with various OSes installed, USB drive, CD-ROM, etc. Nothing boots. This is the last POS Sony I'm buying. It's now literally a brick that converts electricity to heat, and nothing more. Talked with support and at least they're paying to ship it back and get it fixed.