3DS XL Repair Possibly Gone Wrong

So I had 2 broken 3DS XLs, one red, one blue. The blue one had a broken top screen and the red one was broken at the hinge where it opens and closes. I replaced the broken screen of the blue one with the screen from the red one. I then put the motherboard from the red one in the body of the blue one (I figured stuff would still be there like the Nintendo Network ID from the red one). Then, I replaced the blue panels with the red panels. I now have a red 3DS XL that is assembled. The issue is that the power light and charging light goes on but the system itself doesn't (black screens). I tried searching for remedies for the issue but couldn't find anything useful. I used this websites guide on 3DS XL repair to disassemble and reassemble the device. I checked the motherboard and it looks undamaged, all the ribbons seem all the way in too. Any ideas? Did I break it even more?