Remove the five screws around the camera using a Phillips #00 screwdriver.
Remember that we're removing the rear panel, so for this step, only remove screws on the appropriate side of the seam separating the rear and front panels.
The D5100 is held together by a large number of screws, which come in several sizes. Make sure to keep your screws organized so that you don't lose or misplace them!
Remove the dark orange ribbon cable attaching the rear panel to the motherboard by flipping the black plastic clasp up, away from the motherboard, and pull the cable out of its white casing in the direction of the cable.
Using the flat edge of a spudger can help with this delicate task.
Use a Phillips #00 screwdriver to remove the five screws holding the motherboard cover plate. Starting with the right side, lift the plate and remove it from the camera body. Set the plate aside.
Located on top of the motherboard, there are six dark orange ribbon cables. Flip the black plastic lock at each cable up to unlock the cable. Pull the cables straight back away from the white connector to release it.
At this point, the motherboard is able to emerge partially from the main body of the camera, but is still tethered by a few wires.
Using a spudger, slide underneath the twisted red and blue cables and gently pull away from the camera body. This will disconnect them from the motherboard.
Thanks for the guide. I would not have attempted this without your help.
After replacing the main board, the only issue I am having is that the top focus point is not lighting up when I select it. It still works as a focus point, but is not light in the view finder as red. I probably did not perfectly seat one of the ribbon cables. It would be nice if someone new which cable controlled lighting in red the focus dots in the viewfinder.