That's given me a thought...the hole I made in the card allows me to open the lower hatch with my finger or a screwdriver but I've never checked to see if it would also release the top hatch as that has never failed to open (until yesterday).
I shall fiddle somewhat tomorrow if its not too cold or rainy or windy or something.
Has a fiddle. I can confirm that the 20mm access hole I made in the lower tailgate to open the lower tailgate DOES also open the top tailgate. So rear seat folded down and a bit of a stretch and I can release the top hatch if it does it again. I'll have a proper fiddle when the weather improves. Interestingly, I opened the top hatch and flipped the latch that secures it (top of the lower hatch) so the car would think the top hatch was shut but the boot light stayed on.