DIAGNOSIS The TV is in standby mode but not fully booting. This is most often a power supply board issue or a failed main board boot sequence.
FIX Perform a hard power reset. Unplug the TV from the wall outlet. Press and hold the physical power button on the TV (if present) or the joystick control on the back for 30 seconds. Wait 5 full minutes. Plug the TV directly back into the wall outlet, not a power strip. Press the power button on the remote.
IF THAT DIDN'T WORK Check the main board for failed capacitors. Visually inspect the main board (behind the rear panel) for any capacitors with bulging or leaking tops. A failed capacitor on the main board will prevent boot.
HEADS UP Do not repeatedly try to power it on. If the hard reset fails, the issue is internal. The 65NANO75UQA uses an external power brick. Ensure the brick's cable is fully seated in the TV's DC input port.