Boot open warning light.
I had exactly the same problem with the boot open warning light. I guess something goes wrong with the micro switch causing the light to stay on. What I ended up doing was removing the plastic plugs which secure the trim on the inside of the boot lid in the area of the lock/badge. You will find a single wire there which goes to the switch near the lock which you can pull off. This should put the light out, the faulty switch should really be replaced or fixed as you will now be able to open the boot with the key whilst the rest of the car is still centrally locked without triggering the alarm. just make sure you don't close the boot with the keys inside! Hope this helps.