The back cover is very well assembled, you will need the metal opening tool to make enough pressure on the metal tabs.

The side keys are loose, separate them when opening the lid.

Separate the back cover.

Remove the Phillips screw located next to the speakers.

Use the plastic opening tool to pry the plastic frame.

Help yourself with the prong to release the lashes that hold them.

Remove the adhesive that covers the speakers.

Peel off the speakers and separate the plastic frame.

Peel off the battery with the plastic spatula.

Peel off the adhesive holding the handset.

Unsolder the terminals of the handset, applying heat with the tip of the soldering iron while gently pulling the cable.