Black and Decker Hedgetrimmer Problem?

Hi, hope you can help me, i have a set of B&D Hedgetrimmers and until a couple of days ago they worked fine, but as i started cutting my hedge, after spraying with wd40 as always, not the hedge, they seemed to accelerate and then start clicking then they just stopped and now they wont do anything, i have replaced the carbon brushes but to no avail does anyone know what the problem could be, there is not even any energising noise from them, i've checked wires, fuse and gearbox all ok.