Admin has merged two How To's for this issue. The second option starts at Post #40
Over time, the "carbon" buttons on the inside of the remote will wear out (like mine did) where cleaning the circuit board and the button's contact will no longer work without numerous presses on the external buttons.
Until I did this repair, I had to hit the lock/unlock anywhere from 1 to 30 times before it would work.
Give this fix a try if cleaning the insides no longer helps. Of course if you screw up your remote, you are on your own. I know it worked well for me - and I hope it works for you (and saves you buying a new remote and having to get it programmed for your HHR).
(I am assuming the battery solder joints are secure and isn't the problem to begin with - see https://www.chevyhhr.net/forums/how-tutorial-library-21/keyfob-cold-solder-repair-22641/
for details on how to repair broken solder joints at the battery mount)
1) your worn out remote (of course)
2) a very sharp razor/exacto knife
3) a tube of 100% Silicone - I used GE Silicone 1 after testing everything from crazy glue to gorilla glue - nothing else would stick to the silicone keypad inside the remote
4) a toothpick to apply the silicone
5) a silicone keypad from an unused/unneeded device or even a tv remote (I used a keypad from an electronic labeller that was broken)
take the key fob remote apart, and lay it out with your other materials
Select, and cut out one of the rubber buttons from your salvaged silicone keypad
Using the razor/exacto knife - trim off the "carbon" button from the end - cut it THIN, but not too thin. You will want a very thin layer of the gray/white silicone to back the "Carbon"
This is a crappy shot, but it may give you a better idea on how thin/thick to cut it:
Now this step requires a bit of finese - very carefully trim off the existing "Carbon" buttons on the key fob remote - you will need to press it in from the other side to make the button stand up so you can make a clean cut.
Once it is cut off, continue trimming the indentation where the button was, to make the recess a little deeper - the new button will be a bit deeper than the one you removed.
Once the indentations are trimmed back, trim your new Button replacements so they fit the indentation.
Here is a shot taken once the original buttons were removed, and the indentations trimmed a little deeper. One of the original buttons that was cut off and the two new ones (trimmed to fit) are shown here:
Using the toothpick apply a SMALL
drop of the Silicone I to the indentation, and place one of the replacement buttons into it - press it down square, and immediately clean off any excess that squeezes out. DO NOT
GET ANY OF THE SILICONE ON THE WORKING SURFACE OF THE NEW CARBON BUTTON (if you do, remove it, and make a fresh one, and apply it instead)
Let it dy to set up for a couple of minutes, then do the other button, making sure not to disturb the first one.
Let it dry for at least an hour or two - preferably overnight.
Clean the contacts on the circuit board (I use alcohol on a lint free microfibre cloth), reassemble the key fob remote, go out to your car and give the buttons a try.
If it didn't work,
disassemble and inspect the business side of the keypad, for silicone that fouls the button, or the circuit board.
If you mess it up BIG TIME - you can always buy a new remote and swap silicone key pads to save having to get the new remote programmed.