Check the remote control for its infrared emission. Check it with fresh batteries. Check it by pressing all the keys. You can detect the presence of infra-red emission from the remote control, using a cell-phone camera. If you wish to get more details about how to check a remote control, please visit this site. One among the posts has details about it. Surf the site with patience. In some cases, the remote control might need to clean.
http://remotesearch.blogspot.com/
Search the site by type in this key phrase "how to test a remote control "in the "search box at the top right of the display window of the Homepage" to get the related post quickly.
https://www.youtube.com/watch?v=jsSCNCW3IbQ [open and clean]
https://www.youtube.com/watch?v=Qp-l1uh-5gE [open and clean]