In order to determine what the issue is, we have to split the problem into parts, it could be an issue with the control board or it could be an issue with one of the linear actuators, or it could be a problem with the installation.

For #1 please watch this video to determine if it is a control board issue.
http://www.gatekeeperltd.com/how-to-troubleshoot-the-yg-5602-control-board/

For #2 please watch this video to determine if it is a linear actuator issue.
http://www.gatekeeperltd.com/how-to-troubleshoot-the-yg-5602-linear-actuator/

Finally to check the installation, please verify installation was performed in accordance with the manual:

http://www.gatekeeperltd.com/YG5602UE_User_Manual.pdf