I've got a similar issue with a Philips 4K 50 inch Smart TV with Android TV, on a second day of purchase — panel has blacked out with ambilight still glowing (sound wasn't on, so I can't say if it was still working).
I have powered it down and turned back on, it blacked out again, so I turned it off and on with a longer pause, and it worked fine afterwards. I am not yet sure what the issue was, I haven't tried to change HDMI cables yet, but this seems more like software issue so far.
Take it back and get an LG or Samsung , they seem to last the longest and I have seen Phillips go out straight out of the box or a few months down the road. they might look good but won't last like the others do
Refresh rate problem may be ?
Screensaver?
Are you using a high-speed HDMI cable for the connection to the TV?
It may be the backlight in the TV dying. If so Google your TV model + backlight repair to see if you can fix it.
What brand? Is it a Roku TV?
Plugged into a surge protector, UPS, Line Conditioner, or directly to wall outlet?
Check if your HDMI cable is the problem. That's the first thing I would do.
Yeah this model of TV is totally sketchy, It has:
I'm sure there are other issues but can't remember but they are all down to software issues with it being android in most cases :(
Happens in all apps or just one?! Please share specifics.
Happened to my Philips 4k too. Had to take to the service center to get the display panel changed.
I don't know if it helps but same thing was happening on my pc monitor. I thought my monitor was faulty then I found out it was the hdmi cable that causes the problem.
I changed the cable, problem solved