look at the back of the key you see a indent/groove use a small screwdriver and push down and slide the middle bit of the key out it the center bit has 3 clips undo the side with 1 clip and then you will see the battery
iirc the battery is a cr2032 (3v size of a 2p piece ) whats £1.50 - £3 from any decent car shop not halfrauds
you get around 1 min to change it once the batt is out otherwise you will need re-sync the key (tells you how to do this in ya hand book)
if it does go flat you can use your key in the door (imob is a passive device and doesnt use the battery in the key) i found this answer and it worked on my corsa 2003 not sure about 2007 model
steff, January 2010
