I recently bought this new 3ds off eBay saying it would turn on only when charging. And it did work perfectly fine when charging and it shut off when I unplugged it. I assumed it was just a problem with the battery but I tested the battery and it worked fine. I also checked the integrity of the power cables leading from the battery to the motherboard and everything looked fine to me. When I took it apart it looked like someone had tried to do a hardmod on the console (there were blotches of solder on the backside of the motherboard) and I'm wondering if this is where the problem lies. I'll post pictures of the console and anything that looks suspicious, if anybody can find any problems or help in any way that would be awesome! Edit: He did say he tried to read the NAND, but upon reassembly he pinched the battery wire and other wires.