My Fire Stick all of a sudden lost all audio regardless of the TV or audio source that it was plugged in to. I tried resetting the stick and every time when it got to a step in the Setup process the screen would go black. I thought the stick was crashing, but after getting a new stick and having the same issue I finally found the cause. I was using the HDMI extender and it had somehow gone bad. Once I removed the extender both the audio and video issues were resolved!!