Looks like a power supply problem, right? You should check if your power supply is working correctly.
Anyway, it's very common the main board problem. Some SMD components can be broken or a capacitor exploded.
I have the same problem in a 32 inches samsung TV. I'm awaiting from the vendor the two pieces. The power supply normally works, but the mainboard is out of stock in Samsung. So as i think, the problem is in the mainboard.
I'll tell you later if i have resolved the problem to help you better.