DIAGNOSIS The force settings are too low, or there's unexpected resistance causing the opener to think it's hitting an obstacle.
FIX Increase the 'open' force setting.
1. On the motor unit, locate the two adjustment screws. One is for UP force, one is for DOWN force.
2. Find the UP force screw (often marked with an up arrow or 'open'). Turn it clockwise a quarter-turn.
3. Try operating the door. Repeat the small adjustment until it opens fully without reversing.
4. Test the safety reverse by placing a 2x4 on the floor under the door. On closing, the door must reverse immediately upon contact.
IF THAT DIDN'T WORK The problem is mechanical, not electronic. Check for binding: manually disconnect the door using the red emergency release rope and try lifting it by hand. It should move smoothly with minimal effort. If it's stiff, lubricate the rollers, hinges, and springs, and check for bent tracks.
HEADS UP Don't crank the force settings to maximum as a first fix. Excessive force is dangerous. Always find and address the root cause of the resistance first.