turned on secureboot on my z790 ud ac now it dosent work

i was upgradeing my mobo as my old one didnt let me run secure boot. I got the z790 ud ac as it had all the ports and things I needed for my pc. I need secure boot for win 11, as a program I need to use dosent work on win 10. I turned on secure boot and now it dosent work, as in there's no display out and the press key to enter bios state isnt displayed. it has a constant vga light on it, so I asked the online support and they told me to start it with no gpu and 1 ram sick (sill nothing). what shuld I do? return it?