Why does power comes on but no picture or sound

4 - Unplug the input you are trying to use from the TV (such as an HDMI Cable) and plug it back in. 5 - Check for signs of damage on all cords and cables from the TV to all components. ... 10 - Most likely when a TV has the power light ON but NO PICTURE and NO SOUND, it is the Power Supply Board that has failed.Mar 13, 2017
https://www.google.com/search?q=My+TV+come+on+but+no+picture+or+sound&hl=en&tbm=isch&source=iu&ictx=1&fir=0wY3aolUjxDjKM%253A%252Cm308nI5ePisWlM%252C_&vet=1&usg=AI4_-kRhd8kV_tr0wQDsPus5aeL3kzQKEA&sa=X&ved=2ahUKEwifk5OpkYTpAhVCTBoKHdHrATgQ9QEwAHoECAYQAw#imgrc=0wY3aolUjxDjKM:
https://removeandreplace.com/2017/03/13/tv-power-light-comes-on-but-no-picture-or-sound/

Check out the flash light test - if you see an image then the issue is with your inverter board that powers the back lighting.

make sure bulb is,seated fully and all doors properly sealed

on off sensor sounds like its bad

check the oscillator

Hi, you need to get your TV kit replaced... Please reply with the model number of your TV if you repairing it by your own.

that kind of problem needs a tech right away.

make checks in the all power circuits if you are not a tech take it to a repairman