Does anyone know how to clear the message warning light?

My 2007 Ford Galaxy died electrically after a long drive (dashboard, central locking, air-con, etc). I rang the AA for assistance and as I got back into the car and slammed the door, everything powered back up and has worked fine ever since. Shortly thereafter I noticed the warning light flashing in the dash, this only comes on once the ignition is off and the car has been locked. There are no error messages logged in the information section of the cars' menu. I did seem to have a battery issue when I first collected the car (used) but a few long drives seem to have fully charged it up(?).