No screen display and no zoom control.

Recently bought a refurbished canon powershot a560. Have no display on lcd screen (although can review photos). Do initially get menu icons but then these disappear. Have tried pressing display button several times but does not help. I also have no control over the zoom - moving the zoom control has no effect on the lens position. Camera has already been repaired under warranty (back cover repair and camera reset but has failed again after one week). Please help!