A home theater projector is designed to project an imagine that comes from a separate source like a cable box, satellite receiver or computer on a wall or a screen. If you are getting a blank screen with a "No Signal" error message, that means that the projector is not getting a signal from the source. Instead of calling in a technician to fix your problem, you can spend a few minutes troubleshooting the problem and fix it yourself.
Check the video cable connection going into the projector and make sure it is plugged in all the way.
Check the video cable at the source and make sure the cable is plugged in all the way.
Inspect the video cable you are using to make sure it is not broken or frayed.
Confirm that the correct input the source is plugged into is the one selected on the projector. If you have plugged the source into "Video 1" on the projector, then confirm that you have selected "Video 1" as your input.
Check that the source that is sending the signal to the projector is turned on and is working.