Celt, You just described my symptoms to a tee.
Currently my bike is starting.
Last night I took both ground connections loose.
Nothing was even remotely corroded but I did it anyway
Used my dremel tool and a wire wheel. Polished everything even remotely connected to the ground,battery terminals,all leads,engine block,etc.. Di electric grease on all connections. Now I just ride and see what happens.
Mike

If it happens again I'm pulling the starter.