brake lights on by themselves and wont start

Hi, so this has me confused.
Used my 54 mcs yesterday and all was good in the world. Then my neighbor knocks on my door and tells me my brake lights are on. Out I go to check and sure enough they are. I click the remote to unlock it and off go the lights. Then I open the door and the alarm goes off. Turn the key but don't try to start the car and everything seems ok. I go back out a bit later to check and the lights on the dash all light up but the car won't start. Instead the headlights flash and the lights on the dash go out. When I close the door the window stays in its drop position.
Go back out this morning to check the battery and it is a BMW item so guess it is the original but it is showing green = good charge. Try and start it again and nothing but the windows start ratcheting down.

Try it again and then it suddenly catches and runs fine. The clock and trip/mpg have all reset though.

I thought it must be a dodgy battery but now I'm not sure.


Any ideas anyone? It hasn't rained here for the past few days so dont see why it should be a damp fault.