Whenever remote stops working press the circle key and it will again start working.
Also do restart ur box atleast daily to avoid issues, as this is a smart box and there r so many apps and other things continuously working in foreground and background hence there may be times where processor may slow up. There is option to restart box under settings menu on the box. Do make sure whenever u use any app then exit it the right way rather than pressing live key which takes u directly to Live TV mode but app keeps running in background thus creating load on RAM.
Lastly try to unpair and then pair the remote with STB atleast once in 15 days or a month. Just go to settings > android settings > devices and accessories > choose airtel remote option > select unpair key. After this press "option" and "9" key simultaneously which will unpair/refresh the remote and then press "option" and "back" key simultaneously for the remote to enter pairing mode. Now u will see Airtel Remote option appearing under Devices & Accessories tab , just click it and remote will be automatically paired with the XStream Box.
Batteries need changing as per usage and there will be an alert message appearing on TV screen when remote battery reaches low levels