We are having this issue with our 55" TCL Roku TV. We got it from Walmart October 2018, so its 1.3 years old (so expired warranty). TV was working great until earlier we had the CBS All Access app on live tv & noticed the screen was black but could hear audio. Since this happened, we have tried EVERYTHING including the secret code (Home x5, Upx1, reeindx2, FFx2) to reset, unplugging from wall & holding down power on tv for 15 seconds to power cycle then plugging in, holding down physical reset button for 15-20 secs- nothing helps. Now the tv has been reset to factory but can't see the screen. There is no backlight, it's as if the tv is off, but when the white standby light is off & we push buttons we can hear their noises on screen. The weirdest part is most of the time after trying to reset, the "TCL Roku TV" logo will blip onto the screen for a split second before going black again while it finishes reset, & sometimes it does the blinking light reset with no logo flash at all. TCL support had me try all the resets again, but in the end were no help. It feels like a software issue based on what I'm reading but the secret code reset only works for some. Wish I could find out how to roll back an update. But, if I reset to factory settings I would think it would have gone back to the roku version it came with. Would love some help or even just to hear from others with this issue.
