I cleaned the board contacts several times and ordered a new rubber button piece. The horn and decklid work fine although the door locks will work for a short time and then will not. Why will they work just temporarily?

 

Forgot to mention this is a 2012.

 

I have a 2015 Malibu. One key fob I had to replace with a cheaper model on Amazon as the trunk button and horn button rubber is really cheaply made. Had to dismantle it
to put the metal key back in place, so I saw the circuit board. Not impressed by it as it looks pretty cheap, probably China-made. Likely yours is moving around as there is no attachment screw to hold it down, just the FOB shell, would be my guess, Or the C-board has a partial short mayhaps.

 

The cheezy Ebay rubber replacement was no good.
I went to a local key shop https://aaronslockandkey.com/
they sold me another rubber piece and solved the problem. The noticeable difference was the cheezy Ebay pad had a smooth contact surface on the back,
The key shop rubber pads were perforated which seemed to make a difference.