try disconnecting the cable to the dish and see if completes the boot up. If it does check the f connectors are not loose or any stray wires. I that ok, do you have any other boxes connected to the dish? Disconnect them and try again. If still no good your LNB could be faulty. If it still doesnt boot with the dish cable disconnected, you will have to use the box recovery tools using RS232 lead.
Good luck
keith