Right, my Dx light has been brought back, the problem was a loose connection in the light unit, he has fixed it and it works a treat again!
I wander how many lights get binned for something so simple?
The reason the battery looked like it was dead (it didnt light up the voltage reading) was that the protection circuit was basically protecting it from the short circuit on the lighting unit!
I hope this helps some other people who might have thought about shelling out on a new unit when the current one could be repaired, there is bound to be someone you know or even someone through a friend who is good with electronics.