A similar thing happened to me twice. I didn't get any cranking, but when the key was turned, the dash lights didn't go out and the various relays clicked, but nothing else, no drain like when the solenoid kicks in. Worse, it was intermittent. (I had it twice because I didn't replace the female crimp the first time)
Someone, here at Discoweb, had the solution.
It's the low current lead connection on the solenoid. It corrodes. You have to take off the rh (pass side) header (head and down pipe) and unbolt the heatshield. Take off the brown wire, clean up the male spade terminal and cut off the female. Replace the female with another crimp connector (a 'blue' one is correct for the gauge wire) and heat sleeve the whole lot. A gob of dielectric grease on the terminals is a good bet too. It's a fairly simple job, but get a couple of spare studs/nuts for the downpipe flange and a new metal gasket too.
I'd try that because it's only a matter of time before it needs doing and you can eliminate it from the fault finding.....
