need help?? pansat 3500

sorry if i'm repeating my self i don't quite get this yet.
i'm having trouble with my 3500 pansat. it suddenly turned off and within a few seconds turned back on, but tv picture. the box shows "on" only but no channel number. it will not respond to the remote control or buttons on the box. only way to shut it down is by using back switch button or unplugging it. when i do that, it does the samething. any suggestions? much appreciated.