Diagnosis
The safety reversal system is being triggered. On the ChainMax 1000, this is almost always because the infrared safety sensors are misaligned or obstructed.
How to Fix It
Go to the door opening and look at the two small plastic sensors on either side, about 6 inches off the floor. 1) Check that nothing is blocking the lenses (cobwebs, dirt, a box). 2) Look at the LED lights. One sensor (usually the one with the wire coming from the opener) will have a steady green light. The other sensor should have a steady amber or yellow light. If it's blinking or off, they're not aligned. 3) Gently adjust the bracket of the blinking sensor until the light stays steady. The lenses must be pointing directly at each other.
If That Didn't Work
If the lights are steady but it still reverses, the downward force limit might be set too low. On the front of the motor unit, find the two adjustment knobs. The one labeled "DOWN" controls closing force. Turn it up (clockwise) one notch at a time and test the close function.
Heads Up
Never try to defeat the safety reversal system by holding down the wall button to force the door closed. If adjusting the force doesn't fix it, the door springs might be too heavy for the opener, which is a bigger mechanical issue.