Hi Davy, these OLEDs will go into lockdown, especially with display panel faults. Once in lockdown, only the LG service remote will reinitialise them. If you have such a device, press the P-ONLY button while closely watching the screen. The TV should power up briefly then go into lockdown again. During this brief window, if the display panel is faulty, you'll see perhaps a red vertical slash on the screen.
This means the panel is faulty. This has been my experience with these. Bruce