Updating HomePod with new Apple ID password

If you've ever had to change your Apple ID password, you've probably experienced some frustration trying to update your HomePod with the new password, after all, there's no UI or keyboard on a HomePod. You need to use the Home App on your iOS device, but the difficulty is that sometimes the HomePod stops responding to the Home Kit App after you've changed your password and remains unresponsive.

I have multiple HomePods setup in my home as stereo pairs, and when I've tapped on Settings for each of them in the Home App, some of them have correctly prompted me to enter the updated password (with a pop-up), while other HomePods simply remain unresponsive, even after I un-plug and restart them.

What I discovered is, the problem is not with the HomePod itself being unresponsive, the problem is the last known 'state' of the HomePod is cached in the Home Kit App's local memory, so even if you restart the HomePod, the Home App continues to report the prior state as 'unresponsive'.

Solution: The goal here is the clear the memory cache of the Home Kit App on the iOS device. There are probably several ways to do this, but this is how I did it:

1. First, stop/kill/shutdown the Home App by 'swiping up' in the app switcher (the gesture may depend on your device - double-click the Home button or Swipe Up on devices without a Home button).
2. Shutdown and restart your iOS device - You may have noticed in the last few releases of iOS, even killing an app doesn't immediately release it from memory. If you immediately restart the app after killing it, it resumes right where it left off. So to work around this and force clear the memory, hold the power button down and shutdown your iOS device, then restart it.
3. Power on your iOS device and enter your passcode.
4. Start the Home App.

You'll see that the Home App immediately 'polls' each home kit accessory to gather its current state, and when it checks the state of your HomePod, it will see that it needs you to update the password. When you tap into the Settings for each HomePod, it will now prompt you to enter the updated password.

Note: I had to repeat these steps a few times, because while I was updating the password for one of my HomePods, the others would suddenly go unresponsive, but after killing the Home app and restarting my phone, the Home App would re-poll each HomePod for it's current state and eventually I was able to update my password on all of my HomePods.

I believe the bug-fix here is that Apple engineers need to allow the Home Kit app to check on (or poll) the state of each accessory in your home more often, and not cache the state of each accessory. Or, at least have the Home App re-poll the accessory/device whenever you tap into its Settings.

I hope this helps and relieves some frustration with updating your HomePod with a new password.

PS - This was done on HomePod iOS 12.1.2, I have not tested to see if this Home Kit caching issue has been fixed in iOS 12.2