1990 Volvo 760 Back Door problem

[mapleleaf24]

I have a1990 volvo 760. I'm in the process of selling it right now. I have a family that is interested in buying the car however the hatchback door will not open and the family needs it to open for strollers etc. I can't open it from the inside or outside. And the handle on the outside has no resistence at all. Does anyone know if this is an easy fix or how much it woud cost. I would like to either fix it or give the family the information about it. I'm moving out of country soon and need to sell this car!