TCL 65S535 Screen Flickering / Black

I bought a TCL 65S535 65" TV about 2 years ago from Amazon. I've been really happy with it and not had any issues until yesterday when the screen started to suddenly go dark while streaming Netflix. At first it was one side of the screen (about 1/3 of the furthest right hand side), then the other side, then basically the whole screen. It started flickering to very dim, then came on at full brightest for a bit then again the whole screen flickered back to very dim. After about 3 minutes it just went fully dark, but every once in a while it will flicker back to life, ranging from very dim to full brightness. I've tried adjusting the brightness in settings (when I can actually see the screen), cycling the power, checked all the cables to make sure they're tightly plugged in, etc.

I'm worried this is a hardware issue - pretty upsetting for a 2-year old $800 TV!

Any thoughts on how to potentially fix this would be much appreciated.

Daniel C