I recently purchased two N3DSXL units from a guy who intended to swap the screens in them, but "broke them" both in the process. He asked a fair price, so I decided to buy a weekend project. Unit 1 - Broken! - North American N3DSXL * Will not power on (No lights, no popping sounds - nothing) * It WILL charge (orange charging light turns on when plugged in, but won't power on here either) * All the ribbons are connected properly * Tested with three working batteries that work in two other units * Huge Picture: http://imgur.com/0Wy5CwH Unit 2 - Good! - European N3DSXL * This unit simply had the ribbon cables connected backwards for the screens. * After playing with those annoying ribbons... Both screens and all buttons work great. * Powers on, charges. * It works all around! * Huge Picture: http://imgur.com/Dy3HPxz So I swapped parts back and forth between Unit 1 and Unit 2 and tied turning on after each part switch. I learned that... * The ONLY part that DOES NOT WORK IN BOTH UNITS is the motherboard from Unit 1. * The motherboard from Unit 2 will work flawlessly in BOTH units * Both daughter boards (power boards) are good and that all 4 screens are good. Next, I started searching for ways to diagnose the Unit 1 motherboard... I found some threads referencing "Micro Fuses" as being the main culprit in a 3DS (that has all of its ribbon cables intact and connected properly) that does not power on. From what I've learned from various forums... There is one micro fuse on the daughter (power board). And there is one micro fuse on the motherboard near the charging port. So dad dug me out his old Fluke 73 Multi Meter. It does not have the "sound wave" continuity test icon, but it does have a resistance mode to use in its stead (the ohm icon), for testing the micro fuse (As described here on ifixit). Unit 1 motherboard micro fuse (huge pic): http://imgur.com/ZDIlprT Unit 2 motherboard micro fuse (huge pic): http://imgur.com/SnR914e After testing... The micro fuse on both the Unit 1 and Unit 2 motherboards came back the same (0.2 ohm) so I'm guessing the micro fuse is NOT the culprit... Back to square one. The original owner bought Unit 1 (North American Fire Emblem Fates N3DSXL) brand new and tried to swap the top screen (TN panel) for the top screen in the EU model (IPS panel), but after doing so, neither unit turned on. So he swapped them back and put them up for sale. That's all the information that I was given. So here I am, without a clue as to what is wrong with this mother board. Do you guys have any ideas what to test now? Or maybe what I tested was not the micro fuses to begin with? A new motherboard is at least $70USD + shipping + probably 2-4 week wait time (I'm in Canada) And no broken n3ds units are on our local classifieds. So I'm pretty set on fixing this thing if I can. Thanks for reading!