Reconnect HomePod After Wi-Fi Password Update
If you change your Wi-Fi password (same SSID) and your HomePod won't reconnect, try this. On your iPhone, go into Settings > Wi-Fi and tap the ⓘ icon on the name of the network in question. Tap Forget This Network. Reconnect to the network. The HomePod should grab the new conenction from your iPhone within a minute or two. If it doesn't, power-cycle it. If it still doesn't connect, you will probably need to reset it.