I know the glass hatch is probably not especially useful to many folk but, if you find that pressing the button under the rear wiper pivot doesn't release it you may have the problem I did and you may be able to fix it ...for completeness
If you can only pop the glass tailgate by pressing the middle button on the remote key fob it could be poor connections between the button below the wiper pivot and the conductive elements on the glass. The release microswitch completes the circuit that runs along the lowermost 'heated rear window' lines. The microswitches themselves are pretty reliable.
1. Open the tailgate glass using the remote. If you can't do this the problem is something else
2. Using a screwdriver close the latch whilst the glass is open. Only do this if you are certain you can release it using the middle button on the key fob!
3. Remove the plastic cover over the wiper mechanism from the inside of the tailgate glass
4. Complete the circuit between the left and right lowest 'heated rear window' elements. I used one of the leads of my digital multimeter to bridge across. If the latch opens the supply and the conductors on the screen are good from the points tested and the problem is somewhere closer to the switch
5. Check continuity through the switch by connecting a digital multimeter and operating the switch
6. If the switch is good, check continuity between each side of the supply wires for the switch and the relevant screen element
7. If one side or the other (or both) shows no continuity it is a connection problem between the wiring and the screen. In my case it was the connection between the brown wire and the screen element on the right hand side of the car
8. Repair by fixing a jumper wire between the relevant wire at the plug and screen element. The wire end can be soldered, the screen element end can be glued
9. To glue the jumper wire to the screen element scrape a small patch of the coating off the element to reveal a reasonable length of the conductor - say 10mm
10. Bare and tin the end of the jumper wire profiling it so it can lay flat against the exposed conductor
11. Glue the jumper with conductive wire glue that can be bought from a model making shop or electronics repair shop online. Allow glue to cure fully
12. Secure and protect the glued end with insulation tape and route and tape the wire neatly in position so it can be covered by the plastic cover
All being well the switch will now work when you press it
Here's a photo of my fix with the plastic cover removed. The red jumper wire connects the brown wire at the plug to the switch and the screen element on the right hand side of the car. It's tucked and taped so it is fully protected by the plastic cover when it's clipped back on.