It's back to the store to exchange it. If you don't have that option, read the warranty on who to call next.
But even then, a call to the store you bought it from is first.
I bought a FIN43UTV560BK brand new on the 14th of August, 10 days ago that would be. From then until yesterday, everything worked fine, i got both picture and sound when switching between channels, but in the morning today, when i turned the TV on, i got both picture and sound, but i could not switch to another channel. So i tried to search for the channels again, since im using a coaxial connection, but got no channels. But when i switched to another antenna, the channels showed up, and i could switch between them now, but now i only get the sound, no picture (but only a little box on the screen that says ''No video available''). And just to add it, HDMI and everything works fine, i get a picture from my Chromecast, but what do i do now?
Edit: I factory resetted it a few times, and searched for channels on every possible settings, so the problem resolved itself after trying a few times.

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