I just got a 2.1.0-4J 3DS, and I want to update it to 9.2 (for obvious reasons). So, after dumping the OTP and making a NAND backup using Decrypt9, I updated it to 5.1 using a You-Kai Watch cart. Then, I installed RXTools 2.5.2, injected FBI into H&S, and installed SysUpdater. BUT, when I try to launch RXTools DevMode, the 3DS get stuck on a black screen (RXMode works fine). After searching a little, apparently someone had the same problem as me, and he solved it by downgrading to 4.5 with the Gateway Launcher. So I downloaded the correct file, launched GW, downgraded, and... FATAL ERROR 0000100 (or something) at the end. Probably the scariest thing that ever happened to me. Fortunately, it restored my NAND backup (so no brick, yay!), and after some google searching, this error occurs when the console has only been updated with cart. The thing is, I didn't find any way to solve the problem... Some suggest to download an update pack and to install the CIAs with FBI / BBM and then retry, but that doesn't seem like a really safe method (I did the same long ago on my N3DS emuNAND, that bricked it)... So, is there any way to update my 3DS? Thanks!