Power down the mixer and unplug its primary power adapter. Unplug all instrument, speaker and microphone cables from the connectors on the back of the mixer. Allow 10 to 20 minutes for the mixer to cool down if it has been running for a while.
Use a 1/4-inch socket and wrench to remove the 48 nuts on each 1/4-inch input on the back side of the mixer. Unscrew the two Phillips-head screws on each microphone input on the back of the mixer as well. Then remove the remaining Phillips-head screws from the mixer's back side.
Remove each knob from the mixer. Each knob should come free fairly easily with a little bit of force. Unscrew all Phillips-head screws from the top side of the mixer.
Carefully lift the entire cover off the mixer to expose the internal components. Be as gentle as possible when removing the top plate. There are still dozens of wires attached to the bottom side of the plate.