I need to enter our wi-fi password which contains a "!" and I can't figure out how to access that symbol using the keypad on our WorkCentre 3215.
There is no ! at the device, which would mean you need to enter the Key through CWIS, which would mean you need to hook up a wired connection in order to connect to your wireless.
Or run the Wizard and use WPS assuming that is enabled/capable on your router.