why wont my PC detect my keyboard?

I just built a PC and am trying to boot into bios (I have no operating system and I need to change bios settings for my PC to detect my nvme ssd) but everytime I turn my PC on, the keyboard turns on for about 4 seconds then suts right back off, I have tried clearing CMOS and switching to every other USB port on my motherboard but nothing works, and btw my motherboard doesn’t have a ps2 plug, i need a keyboard to work to be able to navigate bios but i cant, ive tried multiple different keyboards in all the usb slots and nothing will work. please help?