Can we get a write up of how to Repair?

The guide mentioned by L Pfaff is not helpful, it teaches you how to take it apart all the way but skips the most important part: Taking the hinge apart and threading the ribbon through the hinge. You need to take everything out of the bottom of your 3ds except for the screen. Then you need to take the top back cover off (4 screws on the inside, slide the cover down and pop it off). After that you need to open the 3ds to not 180°, but one click before that. Then you stick something strong and thin (tweezers) through the hole where the notification led is to pop the hinge out. Then you need to bend the bottom case of the ds slightly to take the two halves apart but CAREFUL! the ribbons on the right side still need to be threaded through the hinge. After that you need to thread the ribbons through the hole that is part of the hinge assembly on the top half of the 3ds, after that take everything out, replace the screen, and do everything in reverse. If you need help you can contact me I am glad to help.

Good Luck!