HomePod (1st generation) won't connect to Wi-Fi after reset

HomePod first generation has lost its network connection.

I have 3 first generation HomePods (Model MQHW2LL/A). One of them has lost its network connection. The other two are working normally. I have been unable to reconnect the malfunctioning HomePod to its network. All 3 HomePods are running version 26.2 (23K54).

I have tried several times to reset the malfunctioning HomePod. When I reach the step to reconnect to the network, I get the message “Unable to join Wi-Fi.” Here’s what I’ve tried (unsuccessfully) so far:

• I tried moving the HomePod to a different location.
• On my iPhone, I tried “Forget this network” on my Wi-Fi network, then rejoining that network.
• I have shut down and restarted my iPhone. 
• I also used Remove Accessory, but then could not use Add Accessory, which requires scanning a QR Code (which this HomePod does not have) or holding iPhone near Accessory because the 1st gen HomePod lacks a wireless symbol. 

So now the Home App does not show the malfunctioning HomePod because it has been removed and cannot be added back.

I have repeated the Reset process, but each time it fails to reconnect to the Wi-Fi network. Meanwhile, the other two HomePods continue to work normally.

The IT tech at the community where I live says that the problem is likely a hardware issue with the HomePod, and advises that I need to buy a new one. Any other suggestions?