Before disassemblying it again you might try to just update the bios, this might rewrite bad sector. Sometimes it rewrites part of the EC for update, worth a try.
Go here :
https://support.hp.com/us-en/driver...otebook-pc-series-touch/8961458/model/8788168
Download latest bios:
F.44 Rev.A
Make sure your battery is atleast 50% , plugin power cable. Close ALL tabs and programs and disable your antivirus until next boot (to not interfere with the bios update)
You can try reinstalling keyboard drivers (this unlikely will help):
-Go to Device Manager and uninstall the keyboard driver, reboot the laptop once uninstalled and it should reinstall the driver automatically upon reboot
If that wont help, disassembly until you see the keyboard connector. Is the connector like in this video? (look around 3mins)
View: https://www.youtube.com/watch?v=XWiidYWJSeg
You can see you need to first "unclip" the plastic clip from the other side of the connector upwards before you remove the connector, and when you put connector back after that you need to "tighten" the plastic clip. There are different mechanisms too, google "keyboard connector laptop" and you can find how.
If you did this all right the first time then do below:
-I would remove the keyboard you have, then blow some compressed air into where the contact pins are underneath, and then use clean toothbrush (need to be new) or whatever new small brush, dip it into isoprophyl alcohol (must be over 80% pure) and softly clean underneat the plastic connector. Let the alcohol dry, shouldnt take long and then connect it again.