My Boxster refuse to start. Have already checked clutch switch, changed battery, jumped it. Everything goes on but the engine wont just crank. The starter relay does click. Ignition switch does seem to be fine. Might be the immobilizer? But I can still unlock the car with the key... Any suggestions?

By the way, where is the starter relay located? And how do I check if the ignition switch really is in good shape?