Make sure you have followed the prerequisite guide of removing the battery before proceeding with this guide.
To remove the back panel, first press and hold the gray button on the back. While doing that also press and slide the panel down and off.
Carefully remove the battery from the phone by prying it from the top.
Pry off the top cover on the back of the phone.
You will then remove the screws from the back of the phone.
Next you will pry apart the two halves of the phone.
Then use the plastic opening tool to remove the motherboard from the front half of the phone.
Next you will peel off the keypad after the motherboard is removed.
Lastly insert the new keypad.