Hello and welcome to Just Answer. My name is Denny; now let me see if I can help you with your Dodge question.
I had this problem with 2 hemi's; in both of my cases, the injectors were leaking, and when started the piston stops against the fluid , but the rest of the motor turns, bending the rod. in both cases the rod in 1 cyl. bent, allowing the piston to then contact the crank, causing the knock/rattle. A coolant leak would cause this also. Possibly, if you would have turned the motor over backwards with a wrench, it would have reversed the fluid lock, and saved the motor.