The picture and sound went out

The picture and sound went out

I have a 70 in RCA roku tv. I had it 16 mos and the picture and sound went out. The power light comes on but that's it. You can press the remote buttons and here them beep. I bought a new power board which is what everyone I've talked to says it was but I installed it today and I still have the same problem. I don't know what else to do.

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