Basically (and as I was a cadet it resulted in me being kinda left in the dark as I cleaned up the mess and snot of lube oil that had build up in the bilge underneath the engine):
Seemed as if the crown got stuck at essentially TDC
Con. rod ripped the wrist pin out and still kept on turning
So the wrist pin and con rod kept punching up and down - beating the hell out of the liner and punching a hole in the block
Liner dust was throughout the engine everywhere, grit was circulated through it all.
Hole in the block let the cooling water pour on into the sump.
Basically hell broke loose inside there, and unfortunately my cadet time was just about up so I missed the big job of cutting the side out of the ship and putting a new engine in.
Also - because this is a compass thruster for DP prime mover it doesn't stop running the same as most engines would when certain alarms and sensors ring off. So it was something to see. heh