Vizio M556-G4 No Backlight

I need some advice here. I've already bought a part that did not fix the issue.

As the title says, I have a Vizio M556-G4 with no backlight.

Some "Experts" on another site stated it was the power board... this turned out to be incorrect.

Upon plugging the power cord in, the Power LED would come on and then fade out after several seconds. So I started doing some research... Which yielded a lot of people stating Power Board was bad. So I went ahead and ordered one. for $30 on eBay.

For diagnostic process...

I took the back off. inspected all of the boards for obvious signs of damage, as well as the ribbon cables. All cables are still held down by the factory tape and there is no visible signs of damage or tampering of any kind.

The Optical Audio LED powers on, and the CPU Heatsink starts to get warm, indicating that there is in fact some power getting to the mainboard at least. I also performed a flashlight test, but was unable to locate any image on my first attempts... I should have been more Thorough with the flashlight test.

Upon receiving the power board I ordered, I installed it, plugged it in and noticed the exact same behavior. No change at all.

So, I figured, okay, the problem has to be with another part. Took the new board out. and reinstalled the original power board. Put the TV back together and did another Flashlight test.

This time I was able to locate an image of the Vizio Logo in the middle of the screen During start up. And after some more searching some text and a countdown timer that was counting down. So, even with the original power board, there is power getting to the mainboard and the LCD screen.

So, at least two components seem to be working fine. the Mainboard and Power Board. That leaves a few other things that may be bad. But I'm not super familiar with what parts may solve this.

The LED Driver board that connects to the top of the Mainboard and powers the LED array. the TCON board, or the LED lights themselves.

Does anyone have any ideas, thoughts or anything? the TCON board seems like it would be fine, considering that doesn't control the backlight, just the LCD screen itself, which appears to be working.

Any advice would be greatly appreciated.

Thank you