Amazon Fire remote is unresponsive in operating Fire TV. I installed new batteries to no avail.
Did you re-pair your remote to the Fire TV? If that doesn't work and you have a smartphone with the Fire TV remote app, go to settings, remotes, and add a new remote. Follow the instructions on the screen.
Here is the relevant help page to Pair the Fire TV remote.
I'm being extremely clever up here and there's no one standing around looking impressed. What's the point in having you all? - Dr Who