Nintendo uses a tamper-resistant screw that requires a tri-wing screwdriver to open. The tri-wing screw is triangular in shape, just as the name suggests, and the screwdrivers are usually not sold in hardware stores. You can buy a tri-wing screwdriver online and they are cheap. However, if you feel comfortable doing things yourself, you can have a homemade screwdriver in just minutes.
Take apart your ballpoint pen. Keep the clear outside shell.
Heat the narrow end of the pen until it becomes soft. If it catches on fire, let the pen burn for a second and then blow out the flame.
Gently press the soft end of the pen into the head of a tri-wing screw on your Nintendo gaming system. After it forms to the screw head's shape, remove it and let it cool.
After the pen cools, insert the formed end into the tri-wing screw and turn it counter-clockwise.
Be extremely careful with the melting plastic. If the burning plastic contacts your skin, it will stick like glue and continue to burn you.