How to install HomePod Software on HomePod (2nd generation) with an IPSW file
Connect HomePod (2nd generation) to a Mac with a supported cable, open Finder or Apple Configurator, then hold Option while you click Restore and choose the IPSW file you downloaded. Only builds marked as signed can be installed.
Only firmware marked as Signed can be installed today. To leave a beta and return to the public release, restore the latest signed release build listed above.
