2015 Denali XL -- Can't get it into Program mode for remote

[docdocgoose]

Hi, new to forums here. My wife's 15 Denali XL only came with one key. I've purchased a new key and have seen the program procedure online and in the owners manual (ours is push to start). I have tried with the working key in the cupholder and passenger seat, put the physical key into the door handle on the driver door and turn it CCW (unlock) 5 times in 10 seconds. I have tried this at least 50 times but it will not go into program mode. Nothing displays on the cluster showing its in program mode. I've watched all the youtube videos on it and looks very easy. I am following the instructions and videos exactly with no luck getting it into program mode. Any ideas? Bad door latch or something? Everything works on the truck; power locks, power running boards, keyless entry, remote start, etc.