Samsung UN50EH5000V unresponsive despite motherboard replacement

Hi all,

I have a 50" Samsung LED Smart TV that recently stopped working. I'll list the symptoms and what I've done so far.

• When the TV is plugged in, it immediately powers on, normally it wouldn't turn on when plugged in.
• The screen is black but the backlights are on.
• The TV does not respond to any commands from the remote or the physical power buttons. The only way to turn it off or on is to unplug.
• After about 15 seconds of being on, the backlights start to flicker.

I've tried:

• Examined all the motherboards for damage, all look good.
• Unplugged the main board and LED board from the power board; the unresponsiveness persisted but the backlight flickering stopped so I thought it was a problem with the power board.
• Replaced with a new power board and issue did not change.

I'm not sure how to troubleshoot from here, I can't seem to isolate the problem. Anyone have experience with this before or know where to point me?