Just a tip, when mine was acting up (sd card reader) i accidentally discovered that the 3ds starts working after i put some pressure on the back cover, the area when you insert the sdcard, and it immediately freezes or gives an Arm11 whenever i let go. So if you want to try it, put a piece of paper close to that area, thick enough to apply sufficient pressure on the sd reader and screw it tightly. It might not work for you, but it's worth a try imo, specially if you don't have an sd reader replacement yet..