How do I diagnose and fix an LCD HDTV whose screen will not come on because of possible lightning strike?

the fact that unit is nor working after a lightning strike means that all that you have done is to no avail and it will co9st more to continue with repairs than to replace the unit
use a quality power surge protector next time

Nobody can predict, what might have been happened to your TV after a lightning strike. Do you thing anybody can? Is any technician have a super-natural power to predict the faults that might have been happened due to lightning (More than 10 Million volts to start on stroke) ? Can you?
Sorry.
Contact the authorized service center. OK?
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get to the screen menu and alter the contrast to lighten up the screen. take it back to the repairer as it may be only be replaceable-not repairable.

The only fix is to replace the panel and that would not be cost effective. It would be cheaper to buy a new TV.

Your Sony Bravia KDL-46S5100 might have been affected and damaged by the lightning strike. You cannot fix it without the help of qualified technician. It must be brought to your nearest service center.

No,Ur power supply board have a big jolt massive power search.It dead,change the power supply board,will solved this problems.Tries Shopjimmy.com,Ebay.com to buy a refurbish power supply board for the replacement.

fixing the tv after a lightning strike is a higly specialized task, you have to deliver it to a qualified tv technician ,there is nothing you can do yourself to fix it

Your TV got fried when the lightning struck. Time to get another one.

This time be sure you plug it into a surge protector power bar, available at radio shack, walmart, any TV or computer store.

If it's been the subjest of a lightening strike chances are the saw tooth capacitor is opened and the main fuse. That's a cheap repair even at a good shop... At the very worst they can diagnose the problem for an estimate and that fee is generally worth the money even if that's not the entire problem.
Bill

Assuming this line is across the screen horizontally (side to side), this means the vertical deflection circuitry is dead. In late model sets, there is a Integrated circuit package which drives the vertical yoke coils. Possible defects: the I.C. itself, bad solder connections where it solders to the board, missing voltage source to this I.C. (often around +24 volts), or a bad electrolytic capacitor in the associated circuitry. This latter often results in a non-linear picture, or less than full deflection condition, rather than a thin line only. It is possible lightning caused this problem, (I've seen some rather illogical damage from lightning ) perhaps it produced enough of a surge to pop the I.C. or a fusible resistor in that voltage source noted above.