Remove all 9 screws on the bottom of the camera and take off the plate, the silver plate underneath, and remove the battery door
Remove the screw in the battery compartment.
Open the card slot door and remove the 2 screws in there.
Open the port covers and remove the 4 screws underneath
Tilt-back the LCD and remove the 1 screw in the top left of the back
Remove the 4 screws around the EVF and the 1 in the diopter
Peel off the leathers on the handgrip, and remove the 2 silver screws towards the back.
Start pull the back panel separate from the body, but don’t completely pull it off yet.
With the camera face down, lift the back panel off and disconnect the ribbon that is connecting it to the board.
Disconnect the ribbon connected to the EVF, then pull the EVF out.
There is some adhesive thermal padding at the back, which is holding it back. Wiggle the EVF to loosen it, and then carefully pull on it to remove it.
Next remove the top. To do so, remove the 2 screws that were behind the EVF. Then remove the screw in the top left, deep in the camera and by the “A7III” label, and the screw in the top-right, by the strap loop mount.
Remove the 2 screws on the sides of the handgrip, next to the front dial.
Disconnect the two ribbons connected to the top
Pull off the top piece of the camera, as well as the port panel.
Begin removing the tape and disconnecting the ribbons. Also remove the screw holding the headphone jack.
Peel the heat tape all the way back to reveal to ribbons by the card readers
Remove the 5 screws holding the board
There are 2 ribbon on the underside of the motherboard, located at the top on the right-side, above the card reader.
There’s another ribbon on the underside of the board, in the lower left corner.
Once everything is disconnected, take out the board
Remove the screws holding the metal heat shielding, and take it off.
Peel back the heat tape from the top and bottom. Be careful peeling it, the tape may pull apart.
Peel off the tape in the lower left corner revealing a screw. Then remove the 3 senor screws.
Take out the sensor.
Be careful when removing the sensor. This camera uses shims to calibrate the sensor, which are very thin metal leaves. If a shim falls out of place or is damaged, your camera will not be able to focus properly.