Renault megane 2005?

My 53 plate Megane has an intermittent problem the tailgate is shut but there is still a message on the display saying "Boot Open". I have shut the boot many times and still the message remains and an annoying beep too everytime you stop at junctions. The central locking won't work so you cannot lock the doors, the interior lights stay on too. Stuck for ideas so any sensible pointers very welcome. Cheers