Is this a travel trailer?
There really is no control board.. if it's like my 2015, there is a switch and a motor + gear box and a cable system that pulls the slide in and out..
Do you have a cover like this? Pull the screws out and check to see if you have power at the motor when moving the switch to extend or retract.
If you do, it's probably the motor. If you hear the motor but it doesn't move then you have a stripped gear box.
20220404_104411.jpg