I have had this issue for a while where the car doesn't recognise when the boot is open. This means the dashboard doesn't show it as open but more annoying it means that if I unlock the car, open the boot and no other doors, then the car locks itself again after a short period. If I still have the boot open, the alarm goes off which is annoying.

 

 

I am having to replace the 3rd brake light and so will be taking the boot trim off for access. Do you think the issue is with the boot lock mechanism? I could replace this but only want to if it could at all cure the issue.

Sounds like the microswitch in the lock mech has failed or not being moved sufficiently/stuck.