Unfortunately, your solution didn’t work for me. For a few hours the + and - were off, but it started again after i asked Siri a question. Also the top gets very hot now, that’s very concerning… I’m now thinking about selling it and getting a stereo pair of HomePod Minis, but I‘m a bit hesitant.
Yes and this happens to me too on occasion. For example, if after watching a movie, I say to the HomePod "Hey Siri, play music." Unfortunately, my solution is not a permanent fix. However, every time I notice the + - staying on I perform my solution and the + - return to normal.
Given when the + - issue reoccurs for me, it appears that the issue is somehow caused by HomePod's confusion with iCloud/Apple Music when switching between its dual role: 1) as a "Home Theater" Audio speaker to the AppleTV; and 2) as an independent iCloud/Apple Music home assistant device. For example, when your commands are driven by the AppleTV and Siri remote, HomePod accesses iCloud/Apple Music through the Apple TV's connection. When your commands suddenly switch and are directed at HomePod Siri, the device then tries to access iCloud/Apple Music through its own internal HomePod connection. HomePod then seems confused as to which iCloud/Apple Music connection it should then use. This appears to cause HomePod to act as if it is still in use...keeping the + - lit, even when the last command has completed. Unpairing the HomePods and restarting the AppleTV seems to break the confusion and reset the connection to iCloud/Apple Music.
Notably, my Kitchen HomePods that are not in use as an AppleTV "home theater" do not suffer from the + - issue...most likely because they operate in a single role. But, if I say to the Kitchen HomePod "play music in the Kitchen and the Living Room," the + - issue sometimes returns to just the Living Room HomePods which are used also for "Home Theater" audio.
I hope Apple fixes this glitch soon.