GD00Z-4 simulates a button press, which momentarily connects (jumpers) the 2 wires to the wall-button. I’ve never hooked mine up but:
test: jumper at the wall button for 1 second - does the door toggle? That is all I would expect the GD00Z to do.
If the jumper works , then I’d expect a loose connection from GD00Z to wall-button.
if the jumper does NOT work, then I’d expect a loose connection from wall-button to door-opener-motor-unit.
You may instead have a short/permanent-accidental-connection in the two output wires from the GD00Z, or from the wall button. In that case, the result is uncertain - for example, my own garage door opener will not toggle until the button is released.
Or you may instead have a wall-button that is not simple. Many people cannot tell what they have just by looking at the exterior. The model of the garage-door-opener-unit should clarify. If there is a “Learn” button on the opener then I expect the wall-button is not simple.
There are several existing threads that deal with this issue.