Your MINI may or may not have a manual boot release cable (it was an option on earlier MINIs), pull up one corner of the base of the rear seat quite hard to release the seat base, there is a ring that you can pull to open the tailgate (if it's fitted), it's in the middle, in front of the rear seatbelt stalks .
Destined to live life £5 behind. Disclaimer
Any advice given is my opinion only, if you decide to act on any advice / info I've given, it's at your own risk!
Plenty of MINIs get this problem (opening, not opening, door open light on etc... etc...), In my experience it's always been caused by some sort of water ingress in-to the electrical system (because of leaks) either in the micro switch in the tailgate handle, or at worst the Body Control Unit which is also a common problem on the MINI again plenty of threads on this (but obviously it could be something else).
As for the cost it can depend on the leak if it is that causing the problem and obviously dependent on what's been effected and if the items can be saved or not (cleaned & sealed, if no long term damage has been caused) just the tailgate switch can be an in-expensive part, the Body Control Unit Ouch! £££££, but if it is a leak the leak / leaks need sorting out as well or it will be a short term fix.
I'm not being negative here but what caused one persons fault may not be the same as yours although the symptoms are the same, so it will be hard for people to advise on that, plus most people will have had the repair done on warranty in the past so again it would be hard for people to advise of cost, In My Opinion.
Sorry! I can't advise on the cost as I do the work myself and I couldn't give a specific figure £££££ because of the reasons above .
Sorry! If the advice doesn't help you it may help someone else .
Destined to live life £5 behind. Disclaimer
Any advice given is my opinion only, if you decide to act on any advice / info I've given, it's at your own risk!
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