Question about Apple HomePod 1st Gen.

I am very happy with my 2 Homepods. I have had them for 3 weeks. Now 1 Homepod no longer works since the weekend. I have no idea. The plus/minus button at the top flashes and there is no connection to the Apple TV or HomeKit. Resetting doesn't work either... with 5 seconds off the mains... and finger pressure until Siri answers. It doesn't answer. Does anyone have any more ideas? Otherwise I'll have to send it in again for "repair" ;-(