First thing is to UNDERSTAND how this thing works. Looks like some people never read owner's manual or checked at Homelink web site.
BTW, my MB SUV does not need to hold down the button. One push and it picks remote fob signal pronto. Nothing to it as far
as set up goes.

 

I agree that checking the Homelink website was helpful, at least for me. It got me in the right direction of how to get the programming working. The owner's manual was a little confusing when attempting to sync Homelink. The instructions aren't particularly clear and a lot of people don't know the type of garage opener they have (ie. rolling code or not). As a first time user of Homelink myself and having read the manual several times, I found myself following the procedure specified in the instructions but it didn't work.

 

Possible that your opener isnt going into learn mode?

 

When I bought my 2017 IS300 Fsport, I brought my garage door remote with me, and the delivery specialist set it up.
Could you just bring your remote to the dealer?

 

You can accomplish one of two pairing steps at the dealership. Pressing the HomeLink
button and then the portable remote button will teach the car the code. The second step
has to be done at the actual garage by pressing the learn button and then the newly
enabled car button.

 

Here is a little piece of information that might keep you from going crazy if your homelink works intermittently after you program it. I recently replaced the garage door opener on my wife's garage - went from a lift master to a Genie unit. After going through the proper programming for the homelink instructions the unit worked perfectly from the car homelink control buttons for her NX200t. Over the course of the next few days, she complained that it would work intermittently - sometimes it would open fine using the homelink button and other times nothing. After some troubleshooting, I found that it was due to the LED light bulbs that I had used in the garage drive unit. If the lights on the unit were off (like opening the door to leave in the morning) the homelink button worked fine. However, after she backed out and pressed the homelink button to close, it would not work - due to the bulbs being on on the drive unit. Once these were turned off, the homelink button worked fine - was able to duplicate 100% of the time by turning the lights on and off. After some research, I found that LED bulbs can interfere with the RF signals of homelink - found in Genie literature where they sell LED bulbs that do not interfere. I just replaced our LED's with the squiggly fluorescents and the problem went away. A bizarre problem - hopefully my experience will save others some troubleshooting time.