Hi. Did one the other day, it’s hold both button for about 10-15 seconds. The WiFi light should blink then connect to it like you said.
They are a pain in the backside to be honest. Some times they will connect no problem and others they won’t. They were originally programmed by ADT with a cable to an android tablet so we had no issues.
Have you got to the stage where it’s asking for the code?