Hi,
It seems like a hardware problem already but here are some troubleshooting steps that may help.
- Start by uninstalling/reinstalling the keyboard driver.
- Go to Device Manager and uninstall the keyboard driver then reboot your laptop. It will reinstall the driver automatically.
- Next is to make sure that Keyboard settings are all set to United States.
- If all these will not work try an external USB keyboard and see if the same problem will persist because if it will not happen you'll need to do a complete factory reset. (Done already)
- And if the factory reset will not work the only solution would be to replace the keyboard itself.