WE M9A1 slide jammed?

[Nick87]

Hi Guys

My girlfriend has jammed the slide it appears on her WE M9A1. The gun was cocked while in safety and it's not returned back to the true rest position, but sits 5mm or so back to the rear. Trigger is in single action position and does nothing. I'm a bit worried about even removing the slide in case I damage something... is this normal, or has cocking in safety messed it up somehow. How should I go about fixing this problem and what was the cause so it can be avoided in future? Many thanks

Nick