Is it possible to program the Countryman without an actual remote but instead use the unit in the garage itself? There is a button to press that should work with the button in the car but it doesn't seem to work.

 

It should work if the unit in the garage is wireless (essentially the same as a remote). Also, you might need a repeater: https://www.northamericanmotoring.co...ster-my-q.html

 

You need a working transmitter to program the car. Wall buttons are usually (but not always) hard wired, so they won't work. Keypads are often wireless, though… if you have one, you could give that a try, but I don't know if HomeLink will successfully program when the transmitter is outside of the car. Of course, if it is wireless you can just unscrew it from the wall and bring it into the car.

If you don't have a working transmitter, see if you can find a friend or neighbor with the same make and model of garage door opener. If your opener is rolling code, then you can just program your car using that remote, then program your opener to your car. If your opener is not rolling code, you'll have to open the remote up to find the DIP switches, take note of what the current settings are, change them to match the configuration on your opener, and then program the car. Be sure to put the switches back before returning the remote.

Or you can just buy a remote online. I've had good luck with aaaremotes.com for whatever that's worth.