Check the engine to chassis earth cable has not broken put a jumper cable from battery negative direct to engine if this works then it is your earth lead ,also make sure your battery leads are clean
Pimbo
July 2013
I would guess the click is the starter motor relay being "called" and operating as it should and the loss of electrics caused by a defective starter motor.
Test the theory by disconnecting any of the big fat wires that go to and from the starter motor.
I am not qualified or experienced to be able to offer you this suggestion - I just guess. Others may know better.