Opening a phone of this scale requires specialty tools. Fortunately, iFixit has got it covered.

Despite its retro aesthetic, this opening procedure is far from obsolete. Some micro spudger action frees up the front clips, and the top plastic plate is free!

We move the keypad aside and find the button pad soldered to the board beneath.

To supply backlight to the keypad, two white adhesive pads diffuse light from four surface-mounted LEDs underneath.