What does a flashing red light mean>

Actually it depends. Which LED is it, lamp, timer, power? Depending which one it is, it will be the issue, if it's the on for the lamp, it's most probable that you may need to replace it sometime soon, if it's the timer, you need to reset the lamp timer, and if it's the power button, well you'll need to put attention to what other symptoms you can notice on the TV