If your Fire TV Stick is stuck on the logo or keeps restarting, Amazon suggests to wait for about 25 minutes for the screen to change. This will let any pending software updates finish installing, and allow background tasks to complete. Do not power off your TV if the Fire TV Stick is downloading an update.
Next, try restarting the Fire TV Stick manually. Unplug the power adapter, wait a few seconds, then plug it back in. It’s also important to note that the Fire TV Stick requires access to a separate AC power outlet — if you’ve plugged the USB charge cable directly into your TV’s USB port, it might not draw enough power to work properly. Preferably, use the cable and adapter that came in the box.
You can also try plugging your Fire TV Stick into a different HDMI port on the TV and see if this fixes the issue. If you’re using the provided HDMI extender, connect the Fire TV Stick directly into your TV’s HDMI port.
To rule out an issue with your TV, test the Fire TV Stick with another TV. If it’s still stuck on the logo, you can try a factory reset. To do this, press and hold the back button and right navigation button together for 10 seconds. Select “Continue” if it appears on the screen. If not, the Fire TV Stick will automatically reset after a few seconds.