Diagnosis
A flashing red status light is the opener's way of telling you it has a problem. It's not a specific error code like some brands, but a general alert. The two most common triggers are the safety sensors being misaligned/blocked, or the travel limits needing adjustment.
How to Fix It
First, look at the two small black sensors near the bottom of your garage door tracks. The little lights on them should both be solid green (or sometimes solid amber, depending on model). If one is off or blinking, something is blocking the beam or the sensors are out of alignment. Clear any debris and gently adjust the sensors until both lights are solid.
If That Didn't Work
The door's 'up' and 'down' travel limits might be off. With the door closed, press and hold the 'Up' button on your wall control. The door should go up and stop when it's fully open. If it doesn't stop correctly, you'll need to adjust the limit screws on the side of the motor unit—consult your physical manual for the location, as turning them the wrong way can damage the door.
Heads Up
Never try to adjust the travel limits by manually forcing the door while the opener is running. You can strip the gears. If the red light persists after checking sensors and limits, the internal logic board might have an issue, and you should call a technician.