(UPDATE) FIXED IT! IT WAS SURPRISINGLY EASY!

You may recall a while back I was having problems with my 3DS. I finally figured out what was causing my 3DS to not boot or occasionally do so but start coming up with errors after a few seconds. I noticed in the iFixIt teardown guide(second pic above) that the red WiFi antenna was above the motherboard if that makes sense. I realized there is a groove that runs along that part of the case or whatever, so I figured the cable's supposed to fit in that groove. The red cable on my 3DS was not in the groove and, wires being wires, tension had pulled it towards all the ribbon cabling and put pressure on the cables running through the hinges. I carefully fished it out and reseated it deeply in the groove to be sure and it's been working fine for 15 minutes so far, the longest I've been able to let it run for a while now. Here's to hoping that was TRULY the problem. Only time will tell.