Surprised you missed these interesting links when you searched for an answer your self, before posting here.
Never mind. This is what I found inside of 60 seconds:
http://www.3dlabellingsystems.com/pages/micra_faulty_boot_switch.html
http://www.rac.co.uk/forum/showthread.php?11181-Nissan-Micro-boot-won-t-open
http://www.theanswerbank.co.uk/How-it-Works/Question1131420.html
http://www.howtomendit.com/answers.php?id=165600
http://howtomendit.com/answers.php?id=73605
https://www.micra.org.uk/threads/our-k12-boot-opening-problems.14422/
Anon, December 2016