Texas Instruments TI-80 Keyboard Mat Replacement

Locate battery cover on the back of the case.

Slide battery cover to the right reveal the batteries.

Remove battery cover.

Slide the red lock down.

Slide the metal tab to the right of the top battery.

Remove the 3-Volt Lithium Coin Cell Battery.

Slide the red lock up.

Slide the metal tab to the right of the bottom battery.

Remove the 3-Volt Lithium Coin Cell Battery.

Using a Torx, T-6 star-bit screwdriver, unscrew four 7.38 mm screws from battery housing.

Unscrew four 7.15 mm screws from back casing.

Using the blue plastic opener tool along the seam of the case, pry off front casing.

Using a Philips PH0 screwdriver, remove the 6 screws. 2 from the top of the Motherboard, 2 from the middle, and 2 from the bottom of the Motherboard.

Using a Phillips Ph0 screwdriver, remove 4 screws from the screen mount.

Using the blue plastic opening tool, pry the Motherboard up.

Using the blue plastic opening tool, pry up the screen from the screen mount.

Check the rubber mat for damage or obstruction at the location of non-functioning buttons.

Flip the mat over to assess dirt and damage.