Keyboard on laptop started double pressing keys and some keys stopped working at all

The keyboard on my HP Pavilion 17 laptop started acting up. For example, when I press A it automatically presses 1, so it types A1. S key does not work along with several other keys. When D is pressed 3 is also pressed, and so on: J7, K8.

Enter does not work; some F keys don't work. For exaple, when I press esc on laptop boot, the menu comes up and I'm unable to choose Boot options because F9 does not work, neither can I enter the BIOS, because F10 doesn't work.

As per some suggestion on the Internet I tried removing battery, pressing down power button for 30 second, and then leave the laptop without battery for 15 minutes. It did not work.

The keyboard has not been spilled on!

Answer

This sounds like a classic shorted out keyboard. To be sure first connect a USB keyboard and make sure that doesn't have the same problem. If the USB keyboard works you should be able to use it to access the BIOS/Boot options or whatever else you would like to do as troubleshooting.

If, however, it's a shorted out keyboard, you will need to look into replacing it. You can pay top dollar to order it from HP... or you can purchase them brand new or refurbished on ebay. Be prepared for a bit of sticker shock. Installing a replacement keyboard in a laptop is not actually that hard usually. Many simply pop out if you know where to apply leverage. Others have screws hidden behind a removable panel directly above the keyboard. Yet others are a combination of the first together with screws on the underside of the laptop. Yours is that last one.

The Pavilion 17 maintenance guide can be downloaded here. The instructions for replacing the keyboard begin on page 56. Be aware, doing this yourself will likely void your warranty (if you still have one). The only special note is that you may have some difficulty getting the new keyboard cable into the slot and locking it in place at the same time... it's just really fiddly. Having an extra set of hands for that part helps immensely.

EDIT: Actually these keyboards are dirt cheap compared to some. The part number you are looking for is 720670-001 (assuming you want a US keyboard) and they go for $10-$20 on ebay/Newegg. I've seen laptop keyboards that cost over $100. Lucky you.