My experience with these is very random, some times they open nicely some time don't. Usually I start from the FAN side an then push it to the front which sometimes work but every time these clips get broken Im close to heart attack. Maybe someone developed some way to always get it done in good...
If you are 100% sure the open-key jumper points are shortened with good setting tor this game region and it still does not boot make sure there's good connection between A & B board. Give it a good squeeze on each of four connectors.