I did tons o troubleshooting things and thought my motherboard was dead on arrival but turns out the 24 pin power cable just wasn’t quite plugged in right and the computer started working after I wiggled it.
I took the CPU cooler off while I was troubleshooting though because it was covering the RAM slots and it’s gonna be an absolute bitch to get back on. I had to get my dad to help me with it the first time and even he had a really hard time with it, it’s super fiddly to get screwed on and the fan clips are quite a tight fit. I hope I won’t have to remove the GPU to get a good enough visual underneath to make sure the cooler is lined up either - it has a clip on it like the RAM slots but it’s a super tight one that you have to press on super hard to remove the GPU. My sister’s boyfriend had to help me with it since I dropped one of the GPU screws deep into the case when I was trying to secure the card and he pressed hard enough that he managed to cut both his thumbs in the process of getting it out.