When I turn it on,no picture?

@leslyjnr first off verify that your TV is a JVC JLC47BC3002. If it is not, then we need to know the exact model number. Next, you will need to let us know where you are pressing. This could easily be a loose wire/connector. As for the no picture, check this first.

Turn the TV to a channel where you can hear the sound. Next, use a flashlight and shine the beam at an angle against the screen. Do that in a darkened room. See if you can make out shadows or shapes. If you do, then it is your backlight that has failed.

If you do not see anything, unplug your set and remove the back cover. Then visually check the boards for any obvious damaged components. Check all the wiring and unplug the wires and plug them back in, make sure they are properly seated. Post some images of all of your boards with your question. Use this guide Adding images to an existing question for that so we can see what you see.