Why does Mighty mule 502 gate opens 2 inch and stops?

Had the same problem with my mighty mule gate opener. First thought the batteries or solar panels wasn't charged or charging ---and that's the spill the manufacturer threw out to me on the first go around---that wasn't the problem--but every time I called them --that's the spill they would start with over and over again solar panel and batteries. I took out the main board myself and exchanged it for another main board from the place I purchased it from (I had someone at the place I purchased the unit who allowed me to exchange the board out to check if the problem was with the main board --he must have known about the problem also) and then it worked for maybe two weeks with no problem then started doing the same thing again. Called the manufacturer about the problem again they basically refused to do anything about it on their dime, wanting me to pay to ship the whole unit back to them charging me to resolve faulty unit issue that they already knew about before placing the junk out into the market to be sold. The manufacturer knows and knew what is and was wrong with this piece of junk. They just don't want to own up to their faulty units and so who knows how many more people got stuck with the mighty mule piece of expensive junk. Maybe now they resolved that problem --don't know. I had purchased this unit several years back and almost right away the gate would do the same thing as your describing--- opening 2 inches and sometimes wouldn't even close or open. Pressing the button and nothing-- then maybe it would open. It was like a fickled person, "well, maybe I'll open the gate or maybe not". "maybe I'll open the gate just a little or maybe not" Very undependable piece of garbage.