mine does this too. you can hear something clicking but it doesn't open till you push the button a couple hundred times. maybe the there is a solenoid in there going out or something.

 

If you hear a click and nothing, I would think that you have a mechanical jam. Problem is getting the damn thing open to lube the latch and check for binding. Maybe take the back seat down to get in there with a screw driver to wrangle it open. Then to check for the binding or what ever is binding it.

 

Update: Unplugged the fuse from inside the car and simply plugged it back in ... started working (on and off) ...
So, I'm thinking its just a worn out fuse.

 

The contacts must not have been in contact enough. Good to hear that its somewhat working.