It sounds like the chain may have gotten a bit "bunched up" at the crank sprocket. No big deal. You may need an extra set of hands to get it free though. Have a helper hold the chain tight on both sides while you turn the crankshaft SLIGHTLY in either direction. If you meet stiff resistance, don't force it. It may take a few tries, but it will free up. This is a common occurence and is nothing to worry about. With the chain free, you'll have plenty of slack on the tensioner side when you re-install the cam sprocket. Good luck and keep us posted.