Samsung pop sound, now tv doesn't turn on (Detailed troubleshooting)

Hi,

First time submitting a question here, hoping some experts can help!

I have an 85" Samsung television (UN85AU800DFXZA - Version No DA09) that I have had for a little over three years.

While watching tv, I heard a popping sound coming from the TV and the TV turned off and would not turn back on. I tried power cycling, but still no power, not even the little red standby light that illuminates where the on/off button is. No breaker popped and I confirmed the outlet was working for other things I plugged in.

I took the back of the TV off and found a burn mark on the power supply board:

I bought a used BN44-01113A Power Supply Board on Ebay and replaced it. When I tried turning the TV on, I now hear a click from the power supply, the audible sound of the tv turning on and the standby/optical sound output has a visible red light! There was still no picture/backlight on the screen. I tried to do the "flashlight" trick to see if I can see a picture if it was the backlight that was failing, but I could not see anything.

I read online that the next issue might be the main board, so I bought a used BN94-17366T Main Board on Ebay and replaced it. When I went to turn on the TV, I no longer heard audible sound of the tv and the red lights no longer illuminated. So maybe the replacement was bad? I am not too sure, so I ended up buying another BN94-17366T Main Board and replaced it. This time I got the audible sound and red lights back, but this time, the backlight also illuminated! I still did not see a picture and the screen has vertical lines in the middle of the screen:

Original Main Board:

Replacement 1:

Replacement 2:

This is where I am stuck now. I have made some positive progress, but I am not sure what to do next...

Is it possible I still have another bad main board? I read that these symptoms could be related to a bad T-Con board, but I am assuming it is included in the main board I have already replaced since I don't see any other boards at least visible on the back of the TV?

I also noticed different "P03, P05, and P07" references next to the BN94-17366T PN on the main board that you can see in the screenshots above. I searched the main board PN here Samsung BN94-17366T Main Board (SEE NOTE) and see my TV PN listed and a bunch of other interchangeable PN's, so I assume the different "P0X" references are fine.

What should I try next??