Keyboard

[Dancingman]

My down arrow is not working 

[BeemerBiker]

See if the part fails during diagnostics:

Tap the ESC key after powering on.
Tap it once a second after you see the LEDs on the keyboard flash.
When you see the startup menu, press F2 to run diagnostics.
If a component fails during the UEFI test then
Click here to check warranty and Click here for world-wide contact info

If the device or part is not listed in diagnostics then update the diagnostics.

HP releases newer UEFI diagnostics periodically.
When you select F2 during boot you are requesting UEFI diagnostics.
There is an updated diagnostics package Click Here
Look for the phrase 'issues outside the OS',
Expand the'+'symbol and click the DOWNLOAD button.

If the device is no longer in warranty then go to the below site, enter your serial number, and locate the part you need to replace.
https://partsurfer.hp.com
For example, if you need a keyboard then use the HP part number to look the part here, or simply search for the part using your browser. Alternately, if only a few keys need to be replaced then just do a key replacement.

Laptop keys can be replaced. Some models are more difficult than others. Usually it is easier to replace a key or two than the keyboard.

There are a number of companies

https://www.laptop-keys.com/

https://www.google.com/search?q=ebay+replace+key+on+hp+laptop

https://www.laptopkeyreplacements.com

https://laptopkey.com/
The above site has videos