Originally Posted by bippym
Not me, I couldn't figure out how to get through the first door
I think a double tap on your fire button should do that.
...or actually it probably starts off locked. Get close to the door, see if your Sonic Key is flashing - that's the little hourglass icon half way down on the right of the screen. If it is, you can use it to interrogate the lock - so hit the fire button and it will work out the code. After that a double tap will send the code, and watch that baby open.
if in doubt check the docs.