Unscrew the four Phillips #00 screws along the top of the back cover.
The screws are held in place by locking washers, and will not come out of the back cover.
The comments section is full of unlucky souls who will tell you that the screws here through step 4 will strip incredibly easily. Press down fairly hard, and go slow.
Hold the device in one hand and turn it over.
Grab the top edge of the back cover with your opposite hand so that the cover does not fall back into place.
Flip the 3DS over again so that the back cover is facing up.
Pull the back cover up and away from the rest of the device to remove it.
Insert a plastic opening tool into the notch in the lower case above the battery.
Pry the battery up with the plastic opening tool.
Grab the top edge of the battery and lift it out of the lower case.
Remove the nine 6.3 mm black
Phillips screws from the lower case.
Remove the 2.4 mm silver Phillips screw above the game cartridge slot.
Lift the bottom edge of the lower case off the rest of the 3DS.
There are still two ribbon cables connecting the mother board to the case, so be sure not to pull the lower case all the way off.
Use a plastic opening tool to pry the shoulder button ribbon cables off their sockets on the motherboard.
Remove the lower case from the device.
Remove the two 7.7 mm Phillips screws securing the back of the
Circle Pad to the motherboard.
Use the flat end of a spudger to pry the back of the Circle Pad off the motherboard.
Lift the Circle Pad joystick off the motherboard and lay it on its back so that the ribbon cable connector is accessible.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the Circle Pad ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, not the socket itself.
Lift the Circle Pad joystick off the motherboard.
To decrease the chance of losing it during repairs, you may want to remove the two thin pads underneath the Circle Pad joystick.
Use a spudger or screwdriver to lift the pads up and remove them from the device.
Remove the two 4.5 mm Phillips screws securing the SD board to the motherboard.
Use the flat end of a spudger to pry the SD board ribbon cable connector off its socket on the motherboard.
Insert the flat end of a spudger between the SD board and the motherboard.
Run the spudger along the sides of the SD board to free it from the adhesive pad holding it in place.
Once completely freed, lift the SD board straight off the motherboard.
Slide the flat end of a spudger under the corner of the Wi-Fi board, and lift it away from the motherboard.
The Wi-Fi antenna cable is still connected to the Wi-Fi board, so you cannot completely remove the Wi-Fi board yet.
Lift the Wi-Fi board off the motherboard and rotate it so that the bottom side is facing up.
Use the flat end of a spudger to pry the Wi-Fi antenna cable connector off its socket on the Wi-Fi board.
Remove the Wi-Fi board from the device.
Grasp the microphone ribbon cable near the microphone with a pair of tweezers.
Pull the microphone straight up out of the upper case.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the speaker assembly ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, NOT the socket itself. Damaging the socket or cable will result in a 3DS that will blink its power LED when you press the power button - and do nothing else.
Disconnect the speaker assembly ribbon cable with a pair of tweezers.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the camera ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, not the socket itself.
When reassembling, note that the gold contacts face toward the motherboard (as opposed to the camera cable's gold contacts facing away).
Remove seven Phillips screws securing the motherboard to the upper case:
Four 2.5 mm gold screws
Two 3.5 mm black screws
One 2.5 mm silver screw
Lift the side of the motherboard that sits along the bottom edge of the 3DS.
Continue lifting the motherboard assembly and rotate it until it is resting next to the rest of the device.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the LCD ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, not the socket itself.
Remove the motherboard assembly from the rest of the device.
Peel the black silicone cover off the back of the D-pad.
Open the 3DS and orient it so that the bottoms of the buttons are facing upward.
Use your finger to push the D-pad through its hole in the upper case.
Remove the D-pad.
The screws are held in place by locking washers, and will not come out of the back cover.
The comments section is full of unlucky souls who will tell you that the screws here through step 4 will strip incredibly easily. Press down fairly hard, and go slow.
Hold the device in one hand and turn it over.
Grab the top edge of the back cover with your opposite hand so that the cover does not fall back into place.
Flip the 3DS over again so that the back cover is facing up.
Pull the back cover up and away from the rest of the device to remove it.
Insert a plastic opening tool into the notch in the lower case above the battery.
Pry the battery up with the plastic opening tool.
Grab the top edge of the battery and lift it out of the lower case.
Remove the nine 6.3 mm black
Phillips screws from the lower case.
Remove the 2.4 mm silver Phillips screw above the game cartridge slot.
Lift the bottom edge of the lower case off the rest of the 3DS.
There are still two ribbon cables connecting the mother board to the case, so be sure not to pull the lower case all the way off.
Use a plastic opening tool to pry the shoulder button ribbon cables off their sockets on the motherboard.
Remove the lower case from the device.
Remove the two 7.7 mm Phillips screws securing the back of the
Circle Pad to the motherboard.
Use the flat end of a spudger to pry the back of the Circle Pad off the motherboard.
Lift the Circle Pad joystick off the motherboard and lay it on its back so that the ribbon cable connector is accessible.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the Circle Pad ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, not the socket itself.
Lift the Circle Pad joystick off the motherboard.
To decrease the chance of losing it during repairs, you may want to remove the two thin pads underneath the Circle Pad joystick.
Use a spudger or screwdriver to lift the pads up and remove them from the device.
Remove the two 4.5 mm Phillips screws securing the SD board to the motherboard.
Use the flat end of a spudger to pry the SD board ribbon cable connector off its socket on the motherboard.
Insert the flat end of a spudger between the SD board and the motherboard.
Run the spudger along the sides of the SD board to free it from the adhesive pad holding it in place.
Once completely freed, lift the SD board straight off the motherboard.
Slide the flat end of a spudger under the corner of the Wi-Fi board, and lift it away from the motherboard.
The Wi-Fi antenna cable is still connected to the Wi-Fi board, so you cannot completely remove the Wi-Fi board yet.
Lift the Wi-Fi board off the motherboard and rotate it so that the bottom side is facing up.
Use the flat end of a spudger to pry the Wi-Fi antenna cable connector off its socket on the Wi-Fi board.
Remove the Wi-Fi board from the device.
Grasp the microphone ribbon cable near the microphone with a pair of tweezers.
Pull the microphone straight up out of the upper case.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the speaker assembly ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, NOT the socket itself. Damaging the socket or cable will result in a 3DS that will blink its power LED when you press the power button - and do nothing else.
Disconnect the speaker assembly ribbon cable with a pair of tweezers.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the camera ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, not the socket itself.
When reassembling, note that the gold contacts face toward the motherboard (as opposed to the camera cable's gold contacts facing away).
Remove seven Phillips screws securing the motherboard to the upper case:
Four 2.5 mm gold screws
Two 3.5 mm black screws
One 2.5 mm silver screw
Lift the side of the motherboard that sits along the bottom edge of the 3DS.
Continue lifting the motherboard assembly and rotate it until it is resting next to the rest of the device.
Use the flat end of a spudger or your fingernail to flip up the retaining flap on the LCD ribbon cable ZIF socket.
Be sure you are prying up on the hinged retaining flap, not the socket itself.
Remove the motherboard assembly from the rest of the device.
Peel the black silicone cover off the back of the D-pad.
Open the 3DS and orient it so that the bottoms of the buttons are facing upward.
Use your finger to push the D-pad through its hole in the upper case.
Remove the D-pad.
