Its not in the blade. Its in the circuit board 100%. Works with proximity. You can take the blade off and stick it in. If the remote is not in proximity it will not start
That's a possible explanation, and I will certainly test it.
How would the key work if the fob battery were completely dead? The key blade and pcb are not electrically connected?
The answer is that it's a magnetic coupled transponder which could be located in the blade.
More info in Wiki
Now I'm really excited to find out if this test works!