Just run my new 2008 353 engine for the second weekend.
Something happened that I have not seen before. The engine broke a rod or the crank and shot the rod through the engine case. Piston is stuck at the bottom and can not even get the backplate off. Picture attached.

Comments Please !

unfortunately there is nothing left to say except the engine is no longer usable

take the heatsink off, remove the sleeve, then pry the piston out.

try and get the backplate of, and the bearings out, and see if they are not damaged. if not buy a new 353 and keep the bearings as spares (only if they are good, i'd be hesitant to use them, but if you are on a budget, then try your luck).

It is possible to close the hole with a 2-component metal glue. When the glue has dryed you can make the inside smooth again. But that has only use when the rest is ok and only a new rod is needed.

i once broke my conrod and it leave 2 dented spots inside my crankcase. anything else is fine. i filed it down and run a new con rod. it last few tanks before totally destroy crankcase,piston,sleeve and conrod. i donno what went wrong in my case. u can try your luck with that engine

Reliability on engines is not 100%. Nothing can ever reach 100% perfect quality, yours might be the .001% of defective engines. Or could've been a bad break-in combined with an over heat or over cold engine.

My suggestion is, take what you can use, Heat sink, carburator and get a new engine.