If your device has been playing continuously for a long time or an update has gotten stuck, you may need to manually restart the stick.
Restart your device
Press and hold the Home (⌂) button on the Fire TV stick remote for a few seconds. A quick access menu should appear covering the entire screen.
Select "Settings."
Select the "My Fire TV" option.
Scroll down and select "Restart."
Select "Restart" again to confirm.
It may take a few minutes for the device to restart. Once you see Amazon homepage, relaunch the VMcast app.
If you had auto launch enabled in VMcast, wait 15-30 seconds. VMcast should automatically restart and begin playing.
You can also force a restart by unplugging the device from the power wall outlet. Wait 30 seconds and plug it back in.