I have a 2003 Mercedes ML 270 CDI automatic that has been sitting for sometime. When I tried to drive it it wouldn't move, felt like the brakes were stuck on, albeit I hadn't left the handbrake engaged. I lifted up the front and removed the disc pads, put the selector into neutral and tried to move rotate the discs by using a bar locked between a couple of wheel studs, but they were solid. Am I doing something wrong? Many thanks