How to latch receiver.
The first picture illustrates where the soldering point is, its on the back of receiver board. Second picture shows where to drop your tin as highlighted, this will make the 1st button your "Hold open" second button is your regular "open and close". Last you need to connected another set of wires to terminal 5/6. The wires in 5/6 will run to "Input" and "GND" the existing wires in 3/4 will move to "Free Exit" and "GND" on the 636.