I have had a remote switch for the light on my backpack for a long time (holding up well!). I thought it would be nice to add a remote switch to the garage door opener.
So, I opened the heat shrink up and soldered
another switch on the remaining two leads in the USB cable. Some more surgery on the other end to attach two connectors. Then open up the garage remote and add wires to each side of the 
momentary push button that opens the door. Taped a block over the original button so it doesn’t get pushed by other things pressing into it.
Connect, and open the garage door. Should have done this ages ago.