Do not mention your son's party again. You don't realize it, but if you do mention it, you are putting pressure on him and it may feel like you are guilting him to come. Put the invitation in with his mail and say absolutely nothing more to him about it unless he brings it up.
As for the garage opener, he may feel that he is still entitled to keep it because there is no paperwork in place as well as he may think he can come there and get stuff out of the garage at any time. Question that I have for you, do you have two garage doors or one? If you have two, unplug the opener for the one he has the opener for. If you only have one door, reprogram the code. Don't ask for the opener again, order a new opener on line...serial number, make and model should be on the opener.
Trust me, unless he has a change of heart, that opener will not be returned to you. Take back the control and either change the code or get a new opener.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
