LG's (at least the LED models) are known for being set almost to torch-mode from the factory, and blowing out or intermittent shorting out LED's. Which causes the power supply to crowbar, and shut down the set. I had that happen to my 2013 3D LG, finally figured out what it was (Youtube video told me), tore down the set and replaced the LED's (NOT easy!), then turned down the brightness quite a bit. That was in January of 2017, and I've had NO issues since then.
It's a hair darker than I'd like, but it continues to work just fine.
Not my exact set, but close enough. Let me warn you though, once you get the actual screen out, it's like trying to hold onto a large thin sheet of ICE, and keeping it from snapping in half or knicking: