You should be able to press the start button with the key fob itself. It has a small transmitter that somehow works even when the battery is dead. just make sure they two are making as close of contact as possible.
AS A FOLLOW UP this is from the 2016 Manual;
If the battery is weak or the smart
key does not work correctly, you
can start the engine by pressing
the engine start/stop button with
the smart key.
The side with the lock button
should contact the engine
start/stop button directly.
When you press the engine
start/stop button directly with the
smart key, the smart key should
contact the button at a right angle.