3DS Power Light Turns on only for a moment. Then Nothing Happens

Hi!

I recently took apart a Japanese 3DS to try to fix a "B" button that wasn't responding. After putting everything back together, I can't get the system to start up: The blue LED light flashes for a moment before going dark. Step 16 of this ifixit guide points to a possibly damaged ZIF socket but nothing seems to be visibly messed up. Feel free to leave troubleshooting suggestions and whatnot since I don't know how fixable this issue is. I've included a couple pictures and a video of the problem below and I can always provide more to clarify things...

Have a good day!