When you read the user manual it should tell you. 

Clue: what’s the power button for?

Yes, the power button can also be used to wake up the speaker from standby. But if it’s not turned off completely and just in standby, also opening the app or putting it in foreground normally should wake up the speaker. But… I recognized that you at least have to do one operation on the app, even it‘s just selecting a room or switching to settings. 
And on the other hand sometimes I wish the app would only wake up the speaker, if you open it after being closed completely before. 

Momentarily lifting MOVE off of its charger ring can get its attention.