Why wont my SKY remote work?

Basically, my grandad has inherited a SKY+ box from his friend and has connected to his Toshiba TV. We have the SKY+HD silver remote, it came with the box and it doesn't work. We've replaced the batteries countless times within the 10 minute mark and it will not control the TV. We've tried all the 'press TV then press select and red together' tasks but it wont work because the remote doesn't affect the TV in any way, not even volume controls. I've suggested we contact SKY but he doesn't think its necessary because they'll only try and get him to subscribe to a package, and we don't want that. We're using the box as a freesat box so we have limited channels, but enough for us.