X Type Jaguar Alarm problem?

The interior light comes on and a message says the drivers door is open. It is not, even if re-opened & slammed again. I have disconnected battery to allow a discharge & reset of the system. It works for a short time but then reverts back to light on & message. I am then unable to use the fob to lock the car - just the key. I am in Portugal & Jags are not common - nor garages. Has anyone a DIY tip that could help, please.