2 Answers

Try tapping the statrer motor with a hammer handle osimilar piece of wood.

If it starts you have a possible couple of problems with the starter.

Either the voltage is dropping and the solenoid is not kicking in, the brushes may be worn (less likely)

A simple fix is to fit a relay at the starter motor (or have one fitted)

This usually cure most starting worries and is not an expensive repair 

The green key icon is for the immobilizer system on your vehicle. Your ignition key has a chip in it and the computer won't allow the engine to start if it doesn't recognize the chip in the key. When that happens, or if there is a malfunction in the system the key indicator light will flash consistently. http://repairpal.com/what-does-green-key-indicator-light-on-dash-mean-616