Facing TV Problems? Ask a TV Technician.
You have said "I receive sound but not picture. The power button won't stay on" -
I am wondering how you get sound if the power button won't stay on??
If you get sound briefly when you turn the TV on, but the TV then turns itself off, then most likely there is a failure in the power supply itself, or in the horizontal scan amplifier, or high voltage section.
A failure in the vertical amplifier could also cause an overload back to the power supply, depending on the nature of the failure.
The TV will require a repair to have the exact cause of the fault located and repaired.