Before starting make sure that the mobile is off.

Remove the SIM tray.

Remove the back cover with the opening tool, this will prevent scratches on the housing.

Remove the 7 Phillips screws (red) that hold the intermediate housing and the 5 screws (purple) of the lower module.

Separate the intermediate housing with the opening tool.

Remove the lower speaker and antenna module.

Disconnect the interconnection flexes from the motherboard.

Peel off the contacts on the left side of the battery that are part of the left flex.

Peel off the battery with the opening tool, prying gently.