Facing TV Problems? Ask a TV Technician.
all are correct except for 6v on P202 - it reads 7.1v - Have not tested 3.4v as I do not know where
That 6 volt supply is NORMAL, And you DO HAVE 3.4 Volts - the TV won't light the backlights if it was dead.
Since you do have backlights, the main board is powering up the power supply, so it's either the MAIN...or the TCON that's causing your problem. Even Techs can't measure that unless it's taken to shop and tested with an oscilloscope. I just bring both boards to the customer's home and try both.
Of course it's an OLDER TV, so I'd make sure both are available on Google