Over the weekend the tailgate failed to open, both main and glass sections.
Both buttons could be heard doing something - just not releasing the catches.
This was all fun and games with hyper kids in a car park and needing to fill the boot with the usual kids related stuff.
Tried the buttons on the dash (holding the lock and unlock both down).
I called my local dealers service guys and they ran through the usual.
In the end I had to get in the boot, over the back seats and pull the plastic/carpet trim off to get to the catches
With the boot closed this was damaged so I've had to buy another one.
Been to my local garage and told it could be a wiring issue of sorts as its odd to have both catches go at the exact same time.

It might only be the upper tailgate latch, I have experienced similar problems in the past and just changed the upper latch. These two doors work together, hence if one fails the other won't open. Try using the fob and press/lock a few times to trigger the lock.

If you can get a fault reading and find the following error, it will definitely be the upper latch.
B1C42-23 (6C) Tailgate release switch 2 - General signal failure - signal stays low

Had this fixed yesterday (on warranty). They replaced the upper micro switch and both boot catches.
I replaced the damaged boot trim, and also while it was off I had the rubber O ring on the lower boot button replaced as well because it was cracked and looked