Flip the board over and you will notice two soldered pins near each letter on the keyboard.

Hold the soldering iron on the pins for a few seconds and remove with the de-soldering pump.

Once both the pins are clear of solder, the pins should move freely in the slots.

When heating the soldered pins, do not let the iron touch the board to avoid any damage.

Do Not Touch the neck of the solder iron when plugged in to avoid any harm.