LG TV turning off automatically may be due to the following reasons:
1. The screen may have been turned off due to [Sleep timer] settings.
Solution: Check the [Duration] setting of [Timer].
If the time set in [Turn off TV after] elapses, the power turns off automatically. To check the settings, press the Quick Settings button on the remote control and select the following in order. Follow the path: [Settings] — [System] — [Power & Energy] — [Energy saver] — [Turn off TV after]
2. If you are the US, CA and MX models, check if [Auto shut-off] in [Power & Energy] is activated.