Hi guys any one able to shed some light on my disco locking me out? (00 v8 disco)

Its done it to me once before about 12 months ago and I left the car for about 4 days and it let me back in randomly.

But last week my alarm went off for no apparent reason and since then its not locking properly (it honks as if a door is open). then if I leave it over night it wont open with the key.

I've had to pull the hood protector off and pop it from under neath. If I leave the battery off for about 2 minutes I can reconnect with the alarm still going off and open the car with the key.

I have a new ish key I had it made when I got the car 2 years ago.

Ideas?

thanks for your help!