Have you tried new batteries? This has worked for a fair number of people.
Have you tried pressing and holding the TV and Rewind button for 10 seconds which will factory reset the TV 360 remote?
Then pair the 360 remote again by holding down the 'TV' button and '0' button together until the Standby button starts to flash. (it should then be automatically detected)
OR Settings > Audio & Video > Pair Remote With Device then select the option for Change TV Setup from there you can manually choose your TV manufacturer and setup the remote control to pair with the TV.
Either use the last 4 characters in the TV model name, or the 4 characters follwoing the screen size.
For example if you had the LG50UQ75006LF you should try either UQ75 or 06LF
Also try the key testing method, Audio & Video > Pair remote with devices > TV devices, but don't just accept the first one that appears to work. Try a few more as (like the older V6 and Tivo boxes) there are often 3 or 4 that will work, some more fully than others.