My R-NZ remote for my Samsung TV will start flashing it's red light non stop and will not work. I encounter this quite frequently and the only solution I've found is to keep removing & reinstalling the batteries multiple times until it decides to work again.
In the forums I've found other people have success with the back button + the up button at the same time for 10 to 20 seconds but this has never helped me. Do I need to replace my remote? It's very frustrating.
There's a quick check to perform to figure out if it's your remote or your TV at fault. Remote is flashing but not responding.
Reset the remote
Check to see if the remote is sending an IR signal.
If you have a Smart Remote, try to pair it with the TV.
Press and hold Return and Play/Pause simultaneously for at least 3 seconds until a message appears on your TV indicating that the remote is now connected.
If the remote will not pair, get your phone out again (or another similar Bluetooth device) and navigate to its Bluetooth menu. (On many phones you can swipe down to open the navigation bar, then touch and hold the Bluetooth icon to open its menu.) Look for your TV on the list of available devices.
* Use the following link to find a list of service centers near you that can do the repair http://www.samsung.com/us/support/service/location.