Took apart-pulled bolt out to get piece of metal left in slot-firing pin in way
Is the piece of metal the rest of the charging handle? I've seen them fly out more than once, but never break off.
If you need to remove the firing pin, there's a small retainer pin that runs vertical through the rear of the bolt, drive it out from top to bottom. Be prepared to catch the firing pin and spring so it doesn't take off to parts unknown.
When you put the retaining pin back in, make sure the ends of the pin sit flush with the bolt body surface.