As usual keyboard failure as we usually seen mostly is due to dusts, smoke waste, dandruff, hair, piece of snacks, liquid spill that settling in the inner surface of the keyboard. Once it get into the bottom of the key, it hard to clean unless you know which button that cause the problem. Actually there is software to test each button of the keyboard which are misfunctional, and when you get the button right, disassemble the key and clean it. Sometimes you can trace many button misfunction but it’s actually one button that caused another button also misfunction. It’s is tough and time consuming .
It’s much more easier and cheaper to get a brand new replacement keyboard than to repair and clean the keys of the keyboard.
But it requires much more work, the palm rest cover need to pulled out and the silver plate that cover the keyboard underneath the frame of the palm rest cover need to be detach in order to replace the keyboard.
The keyboard is held by silver metal plate and glued by plastic rivets and can be snapped back in order to detached the metal plate from the bottom of palm rest cover
Well something to take note, dont lost any screw and clip while you disassemble the cover as after removing the plastic rivets that held the metal plate and the keyboard to the palm rest cover and replace by new keyboard, either you have to find an alternative way to get the metal plate and the new keyboard held back to the palm rest cover or else later you will felt something is loose between the frame and keyboard.
But for this model it is acceptable for not glue back the metal plate and the keyboard to the palm rest cover as long as you put back all the screws and also the clips between bottom cover and palm rest cover well attached.