That is odd? It only happens in P mode? Try it in Auto. If you can get to the settings menu reset it to defaults although I do not think it is a setting problem with that error code your getting. The flash comes completely up? See if you can pull on it lightly, maybe it is not coming up fully.
You can try removing the battery then hold the pwoer switch in the on position for at least 30 seconds then replace the battery and try it again.
See if you can get it to work on any other shooting mode.then turn the flash on and see what happens
Perhaps the flash is a little sticky from not being used and getting it to pop up several times then back down might free it up.
