Amazon Echo Dot (4th gen) with Clock review: The clock-equipped Echo Dot gets a spherical makeover | TechHive
Amazon Echo Dot with Clock (5th Gen) review: Early makeover | TechHive
Echo dot 3rd gen not booting up tried holding the action button for 25 seconds nothing just stuck on the long spinning cyan ring (I'll put what happened in the comments) :
How To Use The Action Button On Echo Dot? - AudioGrounds
What do the Buttons on Alexa Mean - Tom's Tek Stop
Amazon Echo: What Are the Buttons on Top? - Tech Junkie
Amazon's Echo Buttons can now trigger Alexa Routines - Gearbrain