Beware, there will probably be a very large electrolytic capacitor inside that is charged to 300V even when the tv is off. It'll be in the power supply area near where the mains comes in. Discharge this capacitor first, best way is to put beefy resistor across the terminals, maybe 100 Ohm, make sure you don't get your fingers involved.
If you don't know what you're about, don't take the risk. NB freezer spray can sometimes find dry joints, or hot air, you can buy appropriate freezer spray then se if you can initiate the fault ( or cure it ) by spraying different areas. Remember the voltages inside a TV can be lethal.
Andy