Problem with passenger door and boot not opening

Hello! I would be very grateful if someone could help please. I have a 2015 i20, a couple of days ago, I when trying to get in my car, i noticed that the rear passenger door would not open or the boot when I pressed the "open all doors" icon on my key. I then pressed the "open boot" icon on my key fob and the boot opened but the rear passenger door still does not open. All other doors do. I have looked at various threads and I have checked the main car battery, that is OK, charging and holding charge, I have used my spare key fob, that doesn't make any difference. When I "open" the doors, I can hear all doors clicking open and closing so I am guessing there is power getting to them. Would really help if anyone has experienced this and what the fault is and the rectification. Thank so much for reading, your help is appreciated.