My work place had a work truck just die. It was towed to a shop. It would just click, when started. A loose battery cable is all it was. A seized AC compressor will stall the engine. Shut the AC and try to start. Engines don't lock up unless water gets into engine. It's called hydro locked. A engine will seize after running hot with no coolant or oil, or bad oil pump. However, You would have a warning. A broken connecting rod will make noise and happen at higher RPM. I never heard of a broken timing chain on these motors. If it did have a loose chain you hear it. A spun bearing would make some sound.