Is it loose on the top or bottom? The top clips tend to fall apart and need reinforcement. The bottom clips will break when you try to pop the panel off.

How to get it off? Remove the plastic indent that the inside handle is in. Not fun, but it does come off. Then slide fingers or large screwdriver around the bottom to get the clips out of the door. Dealer has new clips!!!

The door ajar light has nothing to do with the panel, unless it was wedged in the door frame. With the door up, push the latch closed 2 positions, I use a phillip screwdriver in the round hole to do this. The light in the dash should go off, if not the micro switch inside the latch is broken which cannot be fixed. Pull the handle to unlock it.

If the light goes out with the latch in pos 2, consider moving the latch bar on the bumper. 2 T40 screws hold down the bar, just move it about 1/16th of an inch rearward. Clean out the dirt first :)

You might want to consider getting new struts, the door should not 'fall' down when closing. There are also some rubber bushings that the tailgate rests on that are probably a bit hard by now.

Klaus
--
Why are Volvos so endearing? Its just a car.