In that you are able to get the camera to turn on, and take a picture with out a lens, then there is some basic problem with the lens attached (essentially across both lenses you have). Also, in that the camera responds when you depress the shutter slightly, the information in the viewfinder is updated (with the lenses attached) - the batteries, sdcard, etc should be ok.
It sounds like you are in auto focus and the camera's autofocus is unable to achieve, or lock focus, thus it will prevent you from taking a picture. Check to see what focus mode you are in. If in Autofocus, is there sufficient light in the area that you are trying to take a picture in? Try taking a picture of a light bulb turned on.
If it does not take a picture in autofocus mode, switch to manual focus, and thus you will bypass the autofocus check. I am thinking that the camera will take the image.
Try again in autofocus mode of taking a picture of something that is black and white in a very well lit area.
If the camera
does take the image in manual focus, and still will not take the image in autofocus, then there probably is a problem with the autofocus circuity and you should exchange the body. The camera uses contrast detection as an indication of locking focus when in autofocus.