My question is ok rtv on the o-ring sure but what in the hell dented your intercooler through the rear throttle opening? If the leak wasn't a bad solder job on the plates i would put money on the front of that core being f'ed up as the cause of the hydrolocking Hard to imagine that a core inside an alluminum manifold could get damaged any time other than during assembly. maybe it got banged while putting it in the manifold.
Edit: or is that just water? hard to tell. I would definitely figure out where that core was leaking from if it just cost you a motor.