Sharp Aquos LC-58Q620U Flashing Red Light

So let me give a little background first. One day my Sharp TV just decided to stop working in the middle of us watching it. The LED light was a steady red. So, After some digging around I decided to try replacing the mainboard. I bought a new mainboard (although this mainboard was advertised as a Hisense - it was the exact same mainboard).

After replacing the mainboard, another issue arose (of course). Now the LED light is continuously flashing red. However, if I hold a flashlight up to the tv I can see Hisense coming up on the screen. It doesn’t go beyond the Hisense logo. I tried seeing if it needed a firmware update. I got firmware from Hisense and followed their instructions but it didnt seem to do anything. Pushing the power button doesnt change anything. The light continues a steady, flashing red light.

So, any ideas what it could be or what I should try? Is it a powerboard issue then? A backlight issue? A short somewhere?

Edit: Actually, holding a flashlight up to the screen I see the Hisense logo turning on and off as well. It almost seems like it isnt getting the power required to keep the Tv on or power the backlights.

I also tried plugging the old mainboard back in just to see if anything changed. Same issue I had before replacing mainboard. Steady red light, try turning it, nothing happens, turns off immediately. Nothing I can see with a flashlight. Its weird one main board yields a steady red light, but the other one has a consistent flashing red light and a picture with a flashlight.