Broken built in blinds in patio door

[Kent Moen]

Our rental property has a back door to the patio with the built in blinds. He called us up today and said that it was broken.

According to him he had probably pulled the strings too hard causing it to break and thereby causing the blinds to be in a closed position with no ability to open them again.  They are great tenants and have taken good care of the place.  It sucks that the view to the back yard is blocked (permanently) by the blinds at the moment.  How would you handle the repair?  Cost?  for the blinds.  I am not sure how to repair this one....

Kent