Veronica Explains on Nostr: I've had this happen before when I've replaced keyboards on used laptops- most often ...

I've had this happen before when I've replaced keyboards on used laptops- most often in my experience it's damage to the ribbon cable which connects the keyboard to the motherboard.

If liquid/gunk/smoke damage got in it, carefully placed contact cleaner can fix it. Sometimes just carefully removing and reseating the cable can also repair it. But if the connector is damaged it might require replacement.