Having trouble with your remote, first remove and reinsert the new alkaline batteries in your remote. then Reset your remote as below:
Place your remote within 10 feet of your Fire TV device.
1 Press the Left, Menus, and Back buttons simultaneously, and hold for 10 seconds.
2 Wait for 60 seconds.
3 Remove the batteries from your remote, unplug your Fire TV device, and wait 60 seconds.
4 Plug your Fire TV device back in, and wait for the Home Screen to display.
5 Press the Home button and Hold about 10-15 seconds, Until the LED starts to rapidly flash then release, waiting about 30-60 seconds(Entering Pair mode, LED Flash), then the remote should automatically pair with your device.
6 IF still not Pair success, please repeat the above 1-5 steps again.
Compatible models:
1. AMZ TV Stick 4K, Lite, 4K Max;
2. AMZ TV Stick (2nd Gen, 3rd Gen);
3. AMZ TV Cube (1st Gen, 2nd Gen);
4. AMZ TV (3rd Gen, Pendant Design).
5. AMZ TV Stick 4K Bundle.
Incompatible:
1. Fire TV (1st Gen, 2nd Gen);
2. TV Stick (1st Gen);
3. Fire TV Edition smart TVs (Such as To shiba/ In signia/ Westinghouse/ Element).