Wondering about SKS & Power button

In case the fob battery dies, the backup method to start the car requires you to press on the brakes and touch the emblem to the power button. Then you can keep on the brakes and press the power button to start the car (or let off the brakes and press the power button to go into Accessory mode). That uses a proximity sensor (like some people have for badges/keys from their employer) that doesn't require any power on the fob side. The relevant portion of the manual is p. 541, "If the electronic key does not operate properly".

Under normal conditions, the battery in the fob powers a transmitter so that you don't have to do this.

 

Concur.
This is why I sometimes opine that it's better just to take the battery out of a third key fobby thingy---if you elect to keep one in your car for emergency ops---like in case you drive off and leave your key fob in your wife's purse, or on a hook in your garage, etc.
Some people also mummify their extra fob in aluminum when they hide it in the car....which I'm told also works well.

Good Luck!

I haven't managed to claw my way through the entire manual yet....