Can't figure out how to lower roof of tent trailer

Please my husband and I have been at this for over an hour now. We cannot seem to get the roof to lower by cranking it down...the "crank" piece won't turn at all. We were told by the owners to turn a "button" beside where we crank first, then start to crank....but we can't get that "button" to turn....please can anyone help up..

What I found on my model 850 is I need to turn the crank slightly to the right to take the load off then carefully and slowly turn the crank to the left to lower the roof.I'm a new owner so I could be wrong but I hope that helps.