Open the back cover.
Lift and remove the battery.
Using a screwdriver (Phillips 1.5 mm PH000), unscrew 8 bolts in the frame of the phone.
Pry and remove the middle frame.
Using a screwdriver (Phillips 1.5 mm PH000), unscrew 3 bolts in the PCB.
Disconnect connectors on the PCB.
Overturn the board, disconnect the connectors from the inside and remove the board.
Disconnect the lower board with inter-board cable and coaxial cable.
The inter-board cable locates under the label, which must be separated with care.