I have an 09 Vantage also and at first I had similar issues with starting and someone told me to push the key flush to the dock with the flat of my finger as I was pushing it a little too far. Then wait for the red ring to appear and push in the key to start, works every time now, good luck

 

I do the exact same thing

 

Get a new battery first.

 

It's more than likely the docking station. My 09' was very intermittent, swapped with my 10' and then my 10' was very intermittent. Bought one off ebay for a 14' Vanquish to test. Out of the box put the ECU in and it would not give it back. Pushed it 20 times it finally released. Pulled out the "plunger" and lubed everything, no change, maybe 30 times to get it out. Wasn't going to risk that again. Realized the electrics were swappable, swapped it and it worked perfect. Tested it in the car and problem fixed. Looked a couple weeks later and there was another one on ebay for $175 so I grabbed it, Tests perfect. I like to keep spares of stuff I'm probably going to need in the next 100,000 miles. New they're close to a grand.