DIAGNOSIS That red light means the TV is in standby mode but isn't booting up. It's usually a power supply hiccup or a software glitch preventing the main board from starting.
FIX This is a hard reset, and it fixes a lot of weird startup issues. First, unplug the TV from the wall. Then, press and hold the physical power button on the TV itself (not the remote) for a full 30 seconds. While still holding it, plug the TV back in. Keep holding for another 30 seconds after it's plugged in, then release. Now try turning it on with the remote. This drains any residual power and forces a clean boot.
IF THAT DIDN'T WORK Check your power cable connection at the back of the TV. On this model, it's a two-piece cable (a cord and a little square brick that plugs into the TV). Make sure both ends of the cord and the brick are firmly seated. A loose connection there can cause the exact symptom you're seeing.
HEADS UP If the red light is blinking, that's a different story—it's an error code. Count the blinks (like 3 blinks, pause, repeat) and look that up, as it points to a specific hardware fault.