Battery Replacement / Car doesn't recognise the key

[tomcampbell393509]

Can anyone help me with this? My brother has a 2012 XF 2.2D which had battery issues recently. He replaced the battery and discovered that the car no longer recognised the key. The car won't start, but all the electrics work. As instructed, he inserted the key into the KVM slot. However, the car still doesn't recognise the key, and the KVM won't release the key. Any ideas?