Having trouble reconnecting with my Homepod

I have first generation HomePod which worked fine until for security reason i changed my wireless network details both the name and Wireless password . Since then, although I have been able ot reconnect every other device , HomePod simply does not want to know. When i press the top, i get "I am having trouble connecting to WiFi".

When i use the Home app on my phone and press add accessory i get a screen with a white rectangle that moves around but pointing it at the HomePod does nothing. When i press "more options" all I get is constant buffering. I can't reset HomePod either as it's not in Home to reset . "My Home" just has that and nothing else