My VDP remote had been a pain on and off ever since I got the car. I’ve repaired it more times than I like to count. This is the later one-button remote BTW, this one.
Problem wasn’t electronic, the issue was physical. The button had (I’m guessing) been previously pressed SO hard that the flimsy plastic “hinge” snapped, leaving the button in the “pressed” position with no bounce-back. As the switch inside needs to be impulsed, without the button springing back the remote couldn’t be clicked, so no go.
The first repair involved re-aligning the tabs of the plastic hinge and carefully applying Krazy glue to the joints, avoiding the female parts of the hinge. Worked for a while, but then one day, re-snapped.
Over the years I repeated that repair many times until the hinge just wouldn’t take it anymore. This last time I thought about getting a replacement but then 
an idea!
All the button has to do is to stay in place and retract after a press, right?
I cut away the broken hinge bits and pulled out the hot-glue gun. Putting a small blob on the hinge end of the button assembly and fitting the top shell back in position I waited for the glue to cool. Any excess glue preventing the case from fully closing I cut away with an Xacto and reassembled the remote. The rubbery hot glue has enough “springiness” to allow the button to pop back up and of course as it’s glued to the case hinge, it isn’t going anywhere. Ever.
Permanent solution!