If you didn't buy a keyboard yet, DON'T!
I followed this guide only to learn at the end that you CANNOT replace just the keyboard (but you CAN put a new keyboard in; keep reading). I specifically bought a keyboard after seeing this guide, and when I got it all taken apart, I learned I wasted my money and time.
This guide should make a correction at the beginning saying that you need MORE than just the keyboard!!!
You can install a new keyboard, but you need to REPLACE THE ENTIRE KEYBOARD COVER as one entire unit: speaker grill, touchpad, etc.
HP routinely designs things to screw customers, and this is a perfect example of it.
The part you need is #859735-001 (red backlit) or #905118-001 (green backlit). Depending where you buy it and how long you want to wait, it'll cost you probably 50 to 100 bucks (China-sourced). There is an unlit keyboard part, IDK the number. Or, buy the HP official part for a lot more, if you can find it.
Good luck!