i have been setting up a hive hub today and there were a few hurdles that i encountered
i think the main issue was getting it to connect to the hive receiver which is hard wired to the boiler
the thing i missed initially was getting the hive receiver to start flashing orange
when you hold the receiver button for 10 seconds the light goes from green to white, which allows it to sync with the thermostat, but once the light is white (non flashing) you then have to hold the button for 10 more seconds to get the flashing orage
there is a pretty slick video describing it here https://www.youtube.com/watch?v=VgFfjRUQ24o