Well, after a couple tries I tightened all black connectors and that did the trick

Yeah… my new 3ds is not working now. It just makes a popping sound and doesn’t charge nor power up.

In step 24:

Use a P2 Pentalobe driver to remove the sixteen 1.5 mm screws securing the antenna assembly.

I can’t remove them with my P2, it looks like they use a different driver. The screws won’t budge with P2.