And so, who now have two black screens, you might be able to fix it by holding "L+R+UP+A" during the boot, which should give you the recovery screen. We already knew about that (so it's not a new method) but as people often brick their 3DS trying to update to the last version (with a rom or other methods, for example), of course, recovery mode doesn't find any new updates and can update the 3DS. But seems you can fix your 3DS is you try to update with a higher update. Here's one example : http://gbatemp.net/threads/bricked-my-n3ds.387735/#post-5471163 The guy tried to update to 9.2 and bricked his 3DS, but managed to update in the recovery mode to the last version (9.7), and now, his 3DS is working fine again. Not the best, of course, but it's better to have a 9.7 working 3DS than a bricked one, as you can always trade/sell the 9.7 one.