2006 S40 immobilizer

[jlturner2708]

I have a 2006 S40 T5. Last week the battery was dead and I ended up replacing it as it wouldn't hold its charge. After installing the new battery, the light, radio, fan, door-locks, etc. all work but the car won't start. The display says "Immobilizer..see owners manual" and then "check skid control (or something to that effect). When I turn the ignition key I can hear a humming sound for about ten seconds which I suspect to be the fuel pump. I've tried using the remote key to lock and unlock the doors five times, to no avail. Any ideas?