If you still have this TV, which was one of the first 1080p LCD TVs ever made, and cost over $2000 in 2005, it might have developed an issue with staying on, or powering up at all. It appears that it is a common issue that progressively gets worse with age. But in most cases it is an easy fix.
The issue is with 2 capacitors on the power supply board, where the solder connection fails, possibly due to thermal expansion. Taking the TV apart, resoldering the capacitor legs and putting everything back together can be performed in under 30 minutes.
Step 1: Disassembly
1.) Remove screws along the perimeter of the frame
2.) Remove small bolts in the middle section
3.) Pull up & away the back cover
4.) Remove the metal cage around the power supply board
5.) Unclip all electrical connectors and remove the power supply board
Step 2: Finding and Fixing Bad Solder Connection
1.) Find the 2 rectangular capacitors on the component side
2.) Flip the board and locate their respective solder connections
3.) Fix the failed connection using some flux + more solder
4.) Reassemble in reverse order and you are done!