How do I know if my Smart LG TV has gone bad, or is it my firestick that I use for it?

Tried to turn on the news, and the picture on my TV blacks out after the usual lights come on. I took the firestick out to see if this was the problem, and there is that clear block that says, "No Signal." So, surely the firestick is whats gone bad, or? I have had it for about 3 years. I pressed "TV on the remote, and it tried to tune the channels (but there were no channels available) and everything else seems to be working as far as the picture and settings go. I hope it's not the TV set and just the firestick. Maybe it got overheated because I sometimes leave the TV on accidentally overnight.

How do I know if my Smart LG TV has gone bad, or is it my firestick that I use for it?
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