gonna sound stupid but cant take photos with new 5N!?

If you had already set the date and time when it asks, that would definitely indicate that the internal battery needs charging.  Weirdly, Sony indicates that most of the internal battery charging goes on during use, rather than whilst the camera is stored with a full battery.

Another oddity to be prepared for if you haven't had a NEX before: occasionally, you'll hear the shutter fire itself about 5 seconds after you turn off.  Don't worry, it's just running an automated routine to check the sensor for hot or stuck pixels which it will then map out during "downtime".  The frequency of this happening varies, based on a complex algorithm which seems to check the passage of time as well as the number of shots that have been taken during that time.  I get it about every two weeks.  The processing goes on "some time later" whilst the camera is turned off and is responsible for the occasional uncharacteristically large overnight drop of the remaining power in the battery (every now and then it'll dwindle by about 15-20% when it was just left unused overnight - under normal circumstances it should only lose about 1% overnight.