Code mostly cloned from https://github.com/kcoppock/bluetooth-a2dp
Reconnecting Bluetooth headphones to Android TV in one click instead of going through menu tree.
Bluetooth device has to be paired already. Its name is hardcoded in MainActivity as BT_DEVICE_NAME
Assign the app to a key on your remote with Button Mapper: Remap your keys -- https://play.google.com/store/apps/details?id=flar2.homebutton&hl=en_US&gl=US