I used to be the 'Convertible top guy' at a very large Volvo Dealership, and the tops would quit a lot, when they were operated with the engine off. What happens is that the Convertible top control unit, see low battery voltage and it just stops so the top does not 'get out of time' with it self and bend all the mechanisms. So, be SURE that your Battery is in REALLY good shape, I mean like new, and ALWAYS have the engine running when you operate the top. I used to have to run to the show to the showroom floor every other day to rescue a sales person, who was trying sell a C-70 Convertible. Be sure and check these basic issues first and foremost.