SLK starting problem
 

Left the car for three weeeks got a flat battery charged it up but still would not turn over so brought a new battery. Everything works great now but the car wont crank up and the lights dim when i try to fire up?
Seems to be a shut off or immobeliser problem. Is there a code for the alarm or a switch for the petrol i need to start it..........Thanks

If the immobilizer is the problem then the starter will work BUT the engine won't start...