I own 4 Sonos Roams, 3 of which are functioning correctly. The fourth Roam, however, has completely frozen.

The only light that is active on the Roam is the microphone light and the device buttons are unresponsive. I cannot reset the device in the usual way turning it off, holding play/pause & pressing power] and it’s not recognized as being connected the rest of my system or as a bluetooth device. 

What are my options to get this Roam functioning again?